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#34 | |
"J. W."
Aug 2021
5·7 Posts |
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Would be interesting if someone could try that again, but without E-core and with AVX-512 enabled. Last fiddled with by JWNoctis on 2021-11-05 at 15:00 |
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#35 | |
"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest
6,469 Posts |
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#36 |
"Composite as Heck"
Oct 2017
19×47 Posts |
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Technically each DDR5 DIMM has two channels, but each channel has half the width relative to DDR4 and all marketing will still call a single DIMM of DDR5 single channel, meaning the basic speeds are comparable between DDR4 and DDR5. Dual channel DDR5 at 3200 is twice the bandwidth of dual channel DDR4 at 1600. The win Alderlake with DDR5 naturally has for benchmarks is that they're specified to work with 4400/4800 speeds, compared to Alderlake and Ryzen specified to work with DDR4 at 3200. Most places will benchmark only at specified speeds, some benchmark with overclocked memory but this is mostly common for gaming which doesn't necessarily tax the memory like Prime95 would (the common overclock being around DDR5 5500, I've seen one that went with DDR5 6000 which looks to be near the fastest available).
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#37 | |
"J. W."
Aug 2021
5·7 Posts |
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Anything much faster than DDR5-6000 might not help much anyway, not with latency. Though I don't know whether that would actually do much, as far as Prime95 is concerned. Next-gen processors with enough cache to run first-time tests without eviction couldn't come soon enough. Last fiddled with by JWNoctis on 2021-11-06 at 01:06 |
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#38 |
"Curtis"
Feb 2005
Riverside, CA
5,279 Posts |
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Prime95 generally saturates memory bandwidth, so any increase in bandwidth via higher speeds is good for our use case. Latency isn't important to P95 speed.
You can test this by changing your own memory latencies in BIOS, if you have motherboard support to do so. Leave speed the same, slow down (higher number) latency, benchmark. |
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#39 |
Aug 2002
33·313 Posts |
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We decided to put together a gaming computer so we could free up our YOLO computer for "real" work.
Several sources claim that DDR4 memory Z690 motherboards are (roughly) as performant as DDR5 motherboards in gaming, maybe because of the increased latency that DDR5 introduces. Given that DDR5 is also impossible to find/buy right now we went with a DDR4 board. We should have the parts within a week or so. Here is what we have ordered so far. CPU: Intel Core i5-12600K 3.7 GHz 10-Core Processor CPU Cooler: Noctua NH-U12A chromax.black 60.09 CFM CPU Cooler Memory: G.SKILL Ripjaws V Series 32GB (4 x 8GB) 288-Pin DDR4 SDRAM DDR4 3600 (PC4 28800) Intel XMP 2.0 Desktop Memory Model F4-3600C14Q-32GVKA Motherboard: MSI MAG Z690 TOMAHAWK WIFI DDR4 ATX LGA1700 Motherboard Storage: Western Digital Black SN850 1 TB M.2-2280 NVME Solid State Drive Case: Fractal Design Define 7 Compact ATX Mid Tower Case Power Supply: SeaSonic FOCUS Plus Platinum 850 W 80+ Platinum Certified Fully Modular ATX Power Supply OTOH, if someone here has a source for DDR5 memory we are willing to switch to a DDR5 build. ![]() |
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#40 |
Aug 2002
33×313 Posts |
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#41 |
Aug 2002
100001000000112 Posts |
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#42 | |
∂2ω=0
Sep 2002
República de California
267178 Posts |
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Best part I found out only in the past month ... when crunching on datasets much too large to fit into the MCDRAM (~200GB of p-1 stage 2 buffers in my case), the 192GB 2400MHz server-ddr4 I installed ($900) comes into play, and my initial timings showed a 2.5x performance hit vs MCDRAM-only. But fiddling with numactl flags I was able to get the OS to make much better use of the MCDRAM as a huge L3 cache, now down to just 1.5x slower than the throughput for the smaller MCDRAM-only dataset. |
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#43 |
Aug 2002
33·313 Posts |
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https://www.anandtech.com/show/16143...-and-latencies
Intel 12th Gen CPU → DDR5-4800 → 38.40GB/s × 2 (dual channel) = 76.8GB ![]() Our YOLO computer → DDR4-3200 → 25.20GB/s × 4 (quad channel) = 100.8GB/s |
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#44 | |
Aug 2002
33×313 Posts |
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Overall, we ended up with DDR4-3600 14-14-14-34 1T Gear 1! ![]() |
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