Those are followed by tRCD, tRP, and tRAS. CAS latency x 2000 / speed. 118. DDR5 still has the highest latencies. It does play a role in latency, but it's more complicated than that. Crucial often has good recommendations on their site and are happy to accept returns. Please consider that I don't mind spending a lot of money for tiny gains in speed. 40 V Frequency= DDR5-6400 (3200 MHz) Primary timings: 32-39-39-102 If the BIOS isn't setting the values properly, you can try setting them manually, in the BIOS. You can think of it as being analogous to memory timings such as CAS latency, etc. Kits with higher speed and lower cas latency perform the best. CAS doesn't even matter anymore. The lower the CAS Latency, the better. Memory 1. ) Still, this doesn't mean you have to choose one or the other. You may ask yourself why would I even choose 5200MHz instead of 6000MHz or even more. Lower values are tighter/more aggressive and possibly more performant. I'm looking at some ddr5 64gb (2x32) ram and I'm down to 2 options. LPDDR5 is very different from DDR5. You can leverage that offset latency. But there is another important factor affecting the performance of RAM, that is RAM speed. The issue with cL is the fact that latency is in its name. There are almost no laptops with XMP, so only look at Jdec timings becausr the Xmp profile cannot be enabled on a laptop. Thank you!! But the Price at the moment just makes DDR5 a very bad deal. TLDR of why from this comment from the video Good video and a great topic. 7 = 619 points 5600cl28 -> 5600/10 = 560 points. [3] In synchronous DRAM, the interval is specified in clock cycles. I can't use it at the stock speed or my computer wont boot. The main difference is ddr4 is common, and We would like to show you a description here but the site won’t allow us. Right? CAS Latency: 6000MHz CL30: 10 ns. As far as I’m aware, the 5xxx number is the higher the better, whereas the CLxx number is the lower the better. Only final performance matter. To compare specific devices you would need to know the specifications, which manufacturers of LPDDR5 devices don’t publish. Normally RAM can work fine slower than its rated speeds, so I would set the timings for your slowest module and let the others work with it. The performance difference of tweaking primary timings on DDR5 is fairly small. You don't need more and you don't want less. Free/g sync helps with that mostly. It's closer than any other DDR5 memory I've seen. With the main difference being bigger quantity versus speed. I don't really want to run into too many issues with crashes, so I was a little apprehensive to go with the higher speed memory. CAS in particular is the number of cycles needed to access the desired position in the RAM and make the data in that position available for the motherboard to retrieve it. On Alder Lake, 1usmus profile works best. So 40 CAS latency on 5200MHz ddr5 means 40 cycles at 5200 MHz, which is 7. Either that or it's just a cost saving measure. winterkoalefant. Skill memory is faster than the corsair ones and why is there almost 100€ difference in kits with exactly same stats. On 3600 MHz, everything below 18 is fast, everything below 16 is really fast. Also get 16gb of ram. For example 3200MHz CAS 16 and 3600MHz CAS 18 have the exact same latency. ~$90 for CL16 3600, or $489 for the CL36 6000 kit HUB used, plus the $10-$30 DDR5 premium of the motherboard itself. Just like DDR4 was not so long ago. In essence, current DDR5 is about 30% slower but performs the same with brute force. 48 GB (2x48) at 7200 speed, 36 CAS latency. First word latency is the coveted attribute now, it seems. Get the Reddit app Scan this QR code to download the app now. Even DDR4 vs 5, you probably get like 10 frames which is not really noticicble. So the faster your cycles (Hz), the more cycles are needed to wait for signals due to propagation delay. [1] [2] In asynchronous DRAM, the interval is specified in nanoseconds (absolute time). • 7 mo. 7200 CL34 is 9. g. With most things ram, it's noticicble if you have a hard number like in a benchmark. Skill DDR5 6400 with a CAS latency of 32. DDR5 Speed and latency. Hey there everybody! Super lucky to have just got in a set of Trident Z5 RGB 6000mhz C40! Just learning and this is my second 6600cl32 -> 9. Lower voltage+higher throughput=higher CAS latency. CAS latency is not that important. com shows the CAS latency is 18. $219. tRCD means "row active to column access", tRP means "row precharge", tRAs means "row active time". When it came to DDR4 RAM, the so-called "sweet spot" was either 3200MHz or 3600MHz at CL16 Latency. also, thats just part of ddr5. Apr 18, 2024 · CL/CAS Latency - Column Access Strobe Latency is the delay between the memory controller requesting data from the RAM and the available data; the first number listed in a kit's timings. Here's a chart you can use to compare latency. ago. Build - Help. The absolute latency (measured in nano-seconds) is likely to be roughly similar to what we have in DDR4 at the moment. 69 nanoseconds per access. Cas latency is important and you should consider it when buying ram. I can get 6000mhz CL36 for £157. Skill F5-7200J3445G16GX2-TZ5RK Memory Type: Unbuffered DDR5 Capacity: 32GB (2x 16GB) Rated Speed: 7200MHz Rated Latency: 34-45-45-115 Tested Voltage: 1. Hi Omen crowd, Looking for some assistance understanding RAM upgrade requirements for my pc. Buildzoid covers it here why Cas latency is a pretty useless timing, especially on ddr5. Skill you get PMIC without cooling (except the heat absorption to PCB lol), and Corsair products are often overpriced for what they are Predator Pallas II DDR5 DRAM Kit: 32GB (16GBx2) Voltage: 1. 5600 CL28 Calculated nanoseconds: 10. This is simply not possible on a DDR4 system. 5B is also a decent test of the timings, but might run at a higher frequency than the IMC is happy with. For your typical AAA title, either XMP profile will produce similar results. TM5 anta777 ABSOLUT, Karhu 10,000%, y-cruncher all tests enabled. 64 bytes begs itself. Having your RAM in a dual-channel configuration improves GPU performance as does having a lower CAS latency (CL) RAM (though less so than the dual-channel -- apparently that's more important. However, using XMP i can lower the speed which also increases my CAS latency. 3: it’s general speed is about 70% higher than DDR4 bringing us from 50-60gb/sec to 90/100gb/sec. Enough for AMD OC's easily. 6ns (initial JDK standard with typical CAS timing at DDR5 launch) DDR5-5600 CAS36: 12. At a theoretical peak of 25. 40v Warranty: Limited Lifetime Mainly, it allows controlling of internal timings on the internal links, between the UMC/Memory controller and the PHY/DIMM interconnect. Fyi this pc is for gaming and heavy music production. 444 ns, almost the same as 3200 CL15 which is pretty good. Because it's new The timings are the number of cycles necessary to perform a read or write operation in the RAM modules. I want to know what the sweet spot is for RAM performance and money spent within DDR5. The thing that makes DDR5 so much better than DDR4 is a few things. Skill Trident DDR5 5600 with a CAS latency of 28 or G. DDR4 is faster than DDR5, but DDR5 makes up for the discrepancy with higher bandwidth. 1: it has a simplified ECC implementation. We would like to show you a description here but the site won’t allow us. 0ns (this new stick for $390) First and foremost you can mix RAM speeds, but it is not guaranteed to work. 0. Why is Cas Latency so high on DDR5 modules. But it's not the absolute latency for that you must take clockspeed into consideration . I am planning to buy a new computer with DDR5 RAM. I’m in the process of buying a motherboard and RAM ready for the x3d launch and I have 2 questions. When it comes to strictly gaming, should I focus more on latency/tight timings or frequency for DDR5 ram? Help Request - RAM I’m currently running my 6000mhz Flare X5 kit at 6400mhz 30-38-38-28 but I’m wondering if I should consider either loosening the timings a bit to hit 6600+ or should I maybe drop it down to 6200 and tighten it some more. This has been consistent across all SDRAM implementations. I’m looking for 2x16GB of DDR5 RAM for a B650 mobo. If you're an old folk, CAS/column latency does not matter as much as it was during the pre-DDR days; it shifted to row activation and cycle, and refresh. On the last Gen, DDR4 RAM kits, we can see CL timings from somewhere around 14 to 18, but on DDR5 It won't have latency issues per-se. 75 ns theoretical latency. 99. It's an Intel build if that matters at all. Suppose it takes 10ns for a signal to change from 0 to 1. So the second one actually ends up being better. 2. I'd say 32GB (2x16GB) of 3200/3600 MTs c16/18 or lower is good enough. DDR4 is also a dead end technology, in that it's not going to get any better or much motherboard support in future. That being said, I would think that if DDR5 latency was a detriment to Ryzen then AMD would not have gone all in on DDR5 for AM5. 7 game average 7700x 6000 mhz cl30 depending on timings is 184 or 190 while cl40 gets175 fps. Yes, the faster speed can overcome the increase in latency. 67ns (I know A bins exist at 14ns but manufacturers don't use them. Lower is better. Some timings may not work. Every new DDR standard sacrifices some latency for higher frequencies. 6800 is definitely a good spot to stop as above that it becomes reliant on silicon lottery. 6. DDR5 has a lower nominal latency. Input lag is dependant on your refresh rate and frame times and maybe response time probably. 3 vs 10 ns is a 33% increase in latency, your transfer at 6000 MT/s runs 87% faster than a 3200 MT/s, which might very well be enough to make up for the increased latency before the transfer started. The importance of CAS latency varies by use case. If you’re looking at building a computer soon, forget even the performance difference - DDR5 is almost impossible to find right now. Remember actual clock speed is half the DDR speed rating. The latency numbers are all in relation to the MT/s, so 7200c36 and 3600c18 have the same latency, at least in the time to the first word. Most HyperX I see available for sale is not at 22 CAS. Like mixed success with Cl20. You also need to take bandwidth into account. A basic DDR4 3200 C16 kit at first seems slower but at C36 the DDR5 would actually be considerably slower. Trying to decide on which G. Hardware Unboxed has a couple recent videos on the subject. Skill 6400CL32 kit is the best, but. Most ram oc really well, so you will be able to push sug a kit to 3600c16/3800c18 fairly easily (if u want). Welcome to /r/AMD — the subreddit for all things AMD; come talk about Ryzen, Radeon, Zen4, RDNA3, EPYC, Threadripper, rumors, reviews, news and more. According to CPUID it looks like this is at 22 CAS latency (and 1. I've noticed that most DDR5 modules have speeds ranging from 4800 to 7000 MHz and CAS latency (CL) between 32 to 40. It all depends on the app and number of threads access to the RAM at a point in time. e. DDR4 has a min burst length of 8 64bit words while DDR5 is 16. 3. - Not on all motherboards they might work, some needs "adjustments". The first word latency is the combination of the two, with the lower the first word latency, the better performing. Reply. Apr 24, 2022 · E. 99 Save -$10. Y-cruncher 2. Oct 6, 2020 · Starting with the lowest data rate, the DDR5-3200A standard supports 22-22-22 sub-timings. 12M subscribers in the pcmasterrace community. 00. From what I've read, the iGPU depends upon the DDR5 RAM for use as video RAM. Dec 31, 2022 · CL30 at 6000MT/s will end up with the same theoretical latency as say CL34 at 6800Mt/s or CL28 at 5600MT/s (though practically the 6800MT/s kit will have the lowest actual latency for reasons I'll get to later). In a few short years, we will see much higher frequency DIMMs with lower latency at a lower cost than current DDR5. However, I cannot tell if the G. 268 ns, which is better than 10 ns. The other question is about AMD EXPO memory. Because X3D CPUs basically don’t care about system RAM speed and you could use DDR5 3600 CL50 and We would like to show you a description here but the site won’t allow us. 6 GB/s bandwidth per channel, this equates to a single access latency of 13. I just found out that Intel i9 only supports up to DDR5 5600 MT/s (5. Smaller We would like to show you a description here but the site won’t allow us. With G. For Ryzen 7000, 6000 MT/s is the sweet spot for memory. the algorithm to calculate is (2000/MHZ)*CAS. in DDR5 I prefer everything else but G. I wanted to get 6000cl30, but most reviews have suggested that the performance difference between it and 6000cl36 is minimal. 99 USD$229. 3200 CL14 is 8. If you have a specific Keyboard/Mouse/AnyPart that is doing something strange, include the model number i. What is CAS Latency and nits for DDR5 ram. May 17, 2022 · Our DDR5-6600 overclock allows us to breach the 100K barrier in read speed, with write and copy speed closer to 90000MB/s. Like some games or applications might only care about the latency, then fast DDR4 is better than DDR5. Read more. Secondly, Dual Channel and "DDR" are separate things. 7 ns first-word latency. 8200 MT/s CL38 has a latency of 9. just like ddr3 to ddr4, latency will be a little worse, especially in early days. That's because AMD guarantees that Ryzen 7 7800x3D (CPU that I will use) can support the speed of 5200MHz (some of the CPUs can go to 6000 or 6600 MHz but that's if you win at the silicone lottery For PC questions/assistance. In this article, we will answer: The first issue that i saw was that this ram has AMD EXPO, and I'm using Intel XMP, but luckily, when i saw the data sheet i saw that it is compatible with both! The second issue was the latency, the one that i ordered it was CL36!! My pc specs are: CPU: i5 14600kf RAM: Kingstone Fury DDR5 6000mhz 16gb CL40 Motherboard: Gigabyte B760M Gaming X Yes, mature DDR4 has lower latency than less mature DDR5. The best ram should have low cas latency and bigger MHz. It’s not even about new information. while 13. . However, in the AIDA64 memory benchmark tool my read speeds never exceed roughly 64000MB/s (latency 66ns), which I think is significantly lower than what it should achieve. If I have to choose a DDR5 module, should I aim for the highest frequency with the minimum CL The formula is clean and easy when you use GHz for the clock speed. RAM timings refer to the number of cycles to complete an operation, higher clockspeed RAM has shorter cycles. My DDR5 kit is KF548C38BBK2-32. It's misleading as it isn't the actual latency of the ram. Lower CAS latencies are helpful for specific tasks, but as I said, it depends on what you are doing. Jan 9, 2023 · Model Name: G. 5200/CL40 has 14ns of latency compared to 10ns of 3600/CL18. ) CAS is not an absolute latency, it's relative to the clockspeed. CORSAIR VENGEANCE DDR5, optimized for Intel® motherboards, delivers higher frequencies and greater capacities of DDR5 technology in a high-quality, compact module that suits your system. 6600 CL32 Calculated nanoseconds: 9. CAS latency varies depending on the clock speed and the number of cycles. So if you have a ram 3200MHz and 16 cas latency you should have: (2000/3200)*16 = 10 Now the smaller the result is,the fastest the ram will be. Because modern DRAM modules' CAS latencies are specified in clock ticks instead of time, when comparing latencies at different clock speeds, latencies must be translated into absolute times to make a fair comparison; a higher numerical CAS latency may still be less time if the clock is Feb 7, 2022 · In simple terms, CAS latency is the number of clock cycles delayed between the moment your CPU sends a data request to RAM and the time this data is available. Not to mention, DIMMs with higher capacities. Dual Channel effectively means your CPU has a separate path to each half We would like to show you a description here but the site won’t allow us. Laptop will have a max speed it can handle as well. 75 ns). (Image credit: Newegg) It’s important to note that two different RAM kits with the same data transfer rate, for example DDR4 The issue is using LTT as a source of info for ram. You'll never be able to directly compare DDR4 and DDR5 on Ryzen so it's kind of pointless to fret about it. If you actually bought that CL22 RAM from a retailer , return it and get something CL16 or lower. If some one could shed light on espceially 6000 is the old sweet spot from like 2 years ago because the chips barely ran that speed and the DDR5 kits at the time were mostly just garbage Samsung and micron that also barely ran 6000. in a year or two, im sure we’ll have much better stuff. CAS Latency is only the first timing, labelled tCL. Faster RAM always has higher latency, and yes the speed makes up for it. Skill Trident Z5 DDR5 RAM sticks to get between these two options: 64 GB (2x32) at 6400 speed, 32 CAS latency. Nov 30, 2021 · How We Tested: DDR5 vs. With DDR5 get the highest frequency your cpu/motherboard can support. for one, its new and not very well tuned. Order today for delivery by 07/23/2024-07/24/2024. When asking a question or stating a problem, please add as much detail as possible. For AM5, I have no idea, I suspect the bandwidth limitation of FCLK will cause issues. skill sticks at $340) DDR5-6000 CAS30: 10. You can get more performance by giving up a little bit of latency in exchange for much higher frequencies. im seeing 32 cas latency and 12 nits is the sweet spot, but what about 30 cas latency and 10 nits? Is the lower the better or is it unnecessary. Go above that and you will end up running some clocks out of sync and overall latency goes to pot. Is CAS latency, first word latency, or overall speed more important for games where lower overall system latency is superior. Meanwhile DDR4 is everywhere. 5600 MT/s CL28 has an actual latency of 10 ns (1/ ( (5600 / 2) / 28)). Column address strobe latency, also called CAS latency or CL, is the delay in clock cycles between the READ command and the moment data is available. But if your cycles are much faster, eg: 1ns, then your latency is now 10, or 10 Just for specs in case it matters, I have a Strix 2080 and 2- WD SN850 SSDs going with it, and cooling the 12900k with the LIAN LI Galahad 360. Cause ddr5 is a lot faster so the real latency zero out so with ddr5 you get about the same latency but a lot more bandwidth. 1. A good gpu and low latency monitor are where you should be focused if gaming is the priority. In short DDR5 has better 'IPC'. Your latency is 2, for 2 cycles. I saw THIS review for DDR5 and at first it looks ludicrous fast at 6000 MT/s but the cas latency seems insane. On a 7800X3D even if you somehow managed to get 6800 to post you’ll see an improvement of … nothing. But if a platform has no option, which any future platform won’t, it’s not about “bothering with” DDR5, it’s a requirement of the platform. But when you measure it in cycles it will be higher, because the frequencies of DDR5 will be higher. Noob here. With that formula the 6600cl32 is 10% "better". You can have Wikipedia shows JEDEC bins and the JEDEC bin for DDR5-6000 is cl50 aka 16. 8ns (current best corsair vengeance module, just fell below $300) DDR5-6000 CAS36: 12. I haven’t seen any DDR5 comparable to 3200C14 for that matter. By the way this sub is about building a PC (see rule 4). 3 days ago · VENGEANCE® 64GB (2x32GB) DDR5 DRAM 6000MT/s CL30 Memory Kit — Black. For video games, games that are heavily tied to the CPU (CPU-bound) may see minor increases in performance with lower latency. DDR5 will in general perform better even if it's higher latency. I've been planning an AM5 build for a little while now (7600+b650+32gb) and I'm trying to figure out what RAM speed and latency I should get. I'm a casual gamer but I mostly use my desktop for productivity and design (3D Blender DDR5 is still faster than DDR4. But DDR5 is twice the bandwidth and has other advantages. EXPO 1 profile is enabled. This is not cost effective. With the recent release of DDR5 RAM, we have much…. I can run my machine with my RAM at 5600 with (if memory serves me) 40 CAS latency, or 6000mhz (currently using this) at 50 CAS latency. Mar 9, 2019 · A listing for a RAM kit on Newegg. DDR5 5200 will be better most of the time, and noticeably better going forward. 32GB (2 x We would like to show you a description here but the site won’t allow us. If you can't, they'll work fine, and you may never actually see the difference. CAS latency is measured in cycles. With DDR5 in particular, primary timings only matter if you plan on doing RAM overclocking. So, the real latency is 8. 2: while it’s CL is much higher than DDR4 it can shoot data twice as often due to a dual bank design. 6600cl32 -> 6000/9. Each 64-bit rank of DDR5 memory (a rank being a subset of memory chips on a memory module) is divided into two 32-bit ranks, with the latency benefits described in At which point you might see a whole 3% bump over 6000! (Assuming the same total latency, so 6800 CL34, and only on a non-X3D Ryzen 7000 CPU. Typical peak memory tech all hovers around the 10-14ns first word latency. DDR5-4800 CAS40: 16. I purchased this ram which has a 6400mhz speed and 32 CAS latency. One is some T-force ddr5 6000mhz cl 38-38-38-78 that's going for $175 and the other is gskill ddr5 6000mhz cl 30-40-40-96 for $210. (Latency in cycles) / (Speed in GHz) = absolute latency in ns. cas (latency timings) should be lower for faster (this is the 45/45/45/45/70 whatever rating, on ddr4 was 14-14-14-14-20 or whatever spec) the ram speed (5000, 5500, 6000 etc) the higher the number the faster the ram. CL = CAS Latency. Corsair Dominator Platinum RGB, DDR5-6200, CL36 - 32 GB CL 36-39-39-76 429€. Memory 2. Also, look at kits that specially state they are for amd expo rather than intel xmp because these are more like to run at their expo profile. I'm wondering how much that difference in timings matters to be worth the extra $25. So people will see DDR5 with CL20 and think it's got a higher latency than DDR4, when in teamgroup tcreate 5600MHz C40 or something similar cheap (some hynix anyway) and enjoy over 7000MHz C32 on Intel. Suppose your cycles are 5ns long. A few questions about A620, 7800x3d, DDR5 Frequency and CAS Latency Build Help Looking to build a mini-itx PC and decided to go with a620 because the cheapest b650 is at least $80 more expensive (NZXT H1 V2, 7800x3d, GIGABYTE A620I AX). It‘s just a crude simplification, but it really isn‘t that important either. To put it bluntly they're pretty inept. Many options have very different prices, ranging from £80-110, all with different specs, such as DDR5-5600 CL36 to DDR5-5200 CL40. The comparison is important to look at for Intel. Posted April 24, 2022. Building a PC for gaming only, I will be playing at 4K ultra. The CL36 modules are EXPO certified but the CL32 are XMP 3. Higher values may improve stability at the expense of Keep in mind CAS latency is usually measured in cycles. I have a question on the DDR5 memory. You want high bandwidth and low latency, that's why I like to do perf = speed / latency. And they are just protocols with wide-ranging performance options. But latency isn't the whole performance. Corsair Vengeance RGB, DDR5-6200, CL36 - 32 GB CL 36-39-39-76 359€. Welcome to the official subreddit of the PC Master Race / PCMR! Similar reasons DDR4 does compared to ddr3, and ddr3 to ddr2. Another reason to go with DDR5 is to take advantage of the new scheduler in Windows 11, which assigns a high and low priority to each task. 75 ns (calculation: 1 / 3200 / 2 * 1000 * 14 = 8. Not only are there lots of other timings, but DDR ram is both read and written in burst mode. But really less noticicble in just everyday use and gaming. 5600cl28 -> 10 ns. Also compare the spread of DDR5 bins to similarily unused bins in previous generations). Skill/Corsair. skill Trident DDR5 6000 CL30. 0ns (slightly faster still somewhat accessible g. That gap is significant imo, ddr5 5200 cl36 gets a bad 163 fps, ddr5 4800 cl40 gets 158 fps. The timings in the image are 52-52-52-103, and you should be able to tighten them up a bit to 32-39-39-102. (CAS: words grew fat due to prefetch; ya're more likely to be content closing that row fer another. 5200MHz CL40: 15,38 ns. My RAM is G. It currently has 2x8 Kingston HyperX (part # HP37D4U1S8MR) DDR 4 3200 clocked at 3733 in the omen gaming hub app. For my scientific calculations, alder lake brought slight improvements in single core speed. I recently built a new PC with a 7800x3d and a Gigabyte X670E Master mainboard. There are exceptions. . 99 (on special) or 6000mhz CL32 for 169. Contrary to our expectations, latency at this 6600MT/s overclock is lower It depends on waht you are trying to use the computer for. From my personal experience, XMP profile 2 should theoretically be better - however it may They do, for ur workload it's also important to have a decent amount of ram. So the DDR5 is clearly better all other things being equal, since the DDR5 has double the bandwidth (disregarding the other small advantages of DDR5). Most of your performance gains come from secondary timings, such as tRRD CAS latency. I’ve been slowly building a pc and im finally buying the ram. 69696969. If there is a choice, DDR5 isn’t a requirement to get good performance. 6 GHz). And then you get more than double the bandwidth. Or check it out in the app stores DDR5 6600 CAS Latency: 32 Timing 32-39-39-76 Memory 2. May 4, 2022 · To throw a brief bit of maths at things, the real-world CAS latency is measured as (CAS Latency x 2,000)/Memory Speed, which in the case of the DDR5-5600 CL28 kit comes in at 10ns. DDR4. 2V if that matters). RAM latency can affect performance, in the sense that it will keep your cpu waiting for data (a well optimised game will try to minimise this waiting), which can lower your fps but the This G. Motherboard supports DDR5 7200 but I don't know if it is worth the money to purchase 32GB at that speed. DDR5 6000 RAM slow speeds. I am deciding between G. 7 game average 13900k 205 fps 7200 cl32 199 fps 6000 cl30 194 fps 5200 cl40 184 fps 4800 cl40 As you can see am5 CPUs care alot about ram while lga 1700 does not. To use anything slower than HUB's kit means you will lose what performance gains they saw, and the latency disparity will also grow which will also lower the scores on the rest of the results even more. jy ul pc jv ak ha lj wr bf lb