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DDR4 3000mhz CL16 and CL15 appears to run in Dual Channel on Intel, but what about Ryzen?

LauRoman
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DDR4 3000mhz CL16 and CL15 appears to run in Dual Channel on Intel, but what about Ryzen?

 

Let me explain first

 

I had an second slightly older machine that had a i5-6500 and a pair of 3000mhz 16-20-20-38 Corsair memory sticks cmk16gx4m2d3000c16 (i will refer to them as CL16). I sold most of it, and i still have the memory.

I have a slightly newer machine 7700k (will be sold eventually for a move to ryzen). It had (has) a pair of 3000mhz 15-17-17-37 Corsair memory sticks cmk16gx4m2b3000c15 (i will refer to them as CL15).

 

If  the channel are numbered, from left to right dimm1, dimm2 dimm3 and dimm4, for dual channel operation, my motherboard should have dimm2 & 4 populated or 1 & 3. Pretty standard so far. I have moved the extra memory from the sold system to the new one as such dimm1=CL16, dimm2=CL15, dimm3=CL16, dimm4=CL15. System seems to have run just fine in dual channel and with XMP enabled.

 

For the heck of it, i took al the memory out and put a CL16 in dimm1 and a CL15 in dimm3. CPU-Z reports it as dual channel. WHY?!? I have checked the spd tab, they are in the correct slots for dual channel and i checked i haven't put identical ram by accident, lol.

 

I will move to a ryzen system sometime in the near future, and memory is probably the last thing i will update, if i do at all. Assuming the channel layout for a ryzen motherboard is identical to what i have now, how would a cofiguration of dimm1=CL16, dimm2=CL15, dimm3=CL16, dimm4=CL15 behave under ryzen?

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3 minutes ago, LauRoman said:

For the heck of it, i took al the memory out and put a CL16 in dimm1 and a CL15 in dimm3. CPU-Z reports it as dual channel. WHY?!?

There is a much larger performance loss going from dual channel to single channel compared to going from CL15 to 16. Motherboards will preserve dual channel functionality and simply nerf the latency to run at the worst timings so the dimms can be used in tandem.

 

Otherwise you're cutting bandwidth in half, not worth it for a nanosecond of improved latency.

I WILL find your ITX build thread, and I WILL recommend the SIlverstone Sugo SG13B

 

Primary PC:

i7 8086k - EVGA Z370 Classified K - G.Skill Trident Z RGB - WD SN750 - Jedi Order Titan Xp - Hyper 212 Black (with RGB Riing flair) - EVGA G3 650W - dual booting Windows 10 and Linux - Black and green theme, Razer brainwashed me.

Draws 400 watts under max load, for reference.

 

How many watts do I need? ATX 3.0 & PCIe 5.0 spec, PSU misconceptions, protections explained, group reg is bad

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14 minutes ago, LauRoman said:

. CPU-Z reports it as dual channel. WHY?!?

more like, why not?

 

14 minutes ago, LauRoman said:

Assuming the channel layout for a ryzen motherboard is identical to what i have now, how would a cofiguration of dimm1=CL16, dimm2=CL15, dimm3=CL16, dimm4=CL15 behave under ryzen?

I hope it's smart enough to follow the CL16 kit's timings, since it's running worse ones.

CPU: i7-2600K 4751MHz 1.44V (software) --> 1.47V at the back of the socket Motherboard: Asrock Z77 Extreme4 (BCLK: 103.3MHz) CPU Cooler: Noctua NH-D15 RAM: Adata XPG 2x8GB DDR3 (XMP: 2133MHz 10-11-11-30 CR2, custom: 2203MHz 10-11-10-26 CR1 tRFC:230 tREFI:14000) GPU: Asus GTX 1070 Dual (Super Jetstream vbios, +70(2025-2088MHz)/+400(8.8Gbps)) SSD: Samsung 840 Pro 256GB (main boot drive), Transcend SSD370 128GB PSU: Seasonic X-660 80+ Gold Case: Antec P110 Silent, 5 intakes 1 exhaust Monitor: AOC G2460PF 1080p 144Hz (150Hz max w/ DP, 121Hz max w/ HDMI) TN panel Keyboard: Logitech G610 Orion (Cherry MX Blue) with SteelSeries Apex M260 keycaps Mouse: BenQ Zowie FK1

 

Model: HP Omen 17 17-an110ca CPU: i7-8750H (0.125V core & cache, 50mV SA undervolt) GPU: GTX 1060 6GB Mobile (+80/+450, 1650MHz~1750MHz 0.78V~0.85V) RAM: 8+8GB DDR4-2400 18-17-17-39 2T Storage: HP EX920 1TB PCIe x4 M.2 SSD + Crucial MX500 1TB 2.5" SATA SSD, 128GB Toshiba PCIe x2 M.2 SSD (KBG30ZMV128G) gone cooking externally, 1TB Seagate 7200RPM 2.5" HDD (ST1000LM049-2GH172) left outside Monitor: 1080p 126Hz IPS G-sync

 

Desktop benching:

Cinebench R15 Single thread:168 Multi-thread: 833 

SuperPi (v1.5 from Techpowerup, PI value output) 16K: 0.100s 1M: 8.255s 32M: 7m 45.93s

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20 minutes ago, Fasauceome said:

There is a much larger performance loss going from dual channel to single channel compared to going from CL15 to 16. Motherboards will preserve dual channel functionality and simply nerf the latency to run at the worst timings so the dimms can be used in tandem.

 

Otherwise you're cutting bandwidth in half, not worth it for a nanosecond of improved latency.

I haven't checked the spec for the CL15 sticks, they probably also support the CL16 timings. Theoretically, if they didn't and the next tier they both commonly support would be something like CL18, they would both run under those specs, right? Motherboards are not intelligent enough to automatically (and no user presets) run memory out of spec, right? I'm asking, because i haven't run mixed dual channel memory since 2010-2011 and ddr2/lga775.

10 minutes ago, Jurrunio said:

more like, why not?

 

I hope it's smart enough to follow the CL16 kit's timings, since it's running worse ones.

I hope so too, but i have yet to own anything ryzen, hopefully to be remedied by year's end.

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38 minutes ago, LauRoman said:

I haven't checked the spec for the CL15 sticks, they probably also support the CL16 timings. Theoretically, if they didn't and the next tier they both commonly support would be something like CL18, they would both run under those specs, right? Motherboards are not intelligent enough to automatically (and no user presets) run memory out of spec, right? I'm asking, because i haven't run mixed dual channel memory since 2010-2011 and ddr2/lga775.

For the most part that pair should operate at 16, given what I've seen. There doesn't seem to be a need for explicitly support at a given timing for that compatibility

I WILL find your ITX build thread, and I WILL recommend the SIlverstone Sugo SG13B

 

Primary PC:

i7 8086k - EVGA Z370 Classified K - G.Skill Trident Z RGB - WD SN750 - Jedi Order Titan Xp - Hyper 212 Black (with RGB Riing flair) - EVGA G3 650W - dual booting Windows 10 and Linux - Black and green theme, Razer brainwashed me.

Draws 400 watts under max load, for reference.

 

How many watts do I need? ATX 3.0 & PCIe 5.0 spec, PSU misconceptions, protections explained, group reg is bad

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