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X470D4U - Adjust RAM voltage£

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icanhazhax View Drop Down
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    Posted: 05 Jun 2021 at 11:40am
I have an ASRock X470D4U (in 1U4LW-X470 chassis) and I'm trying to get my RAM to run at its rated speed of 1.35 Volts. I found out how to adjust the RAM timings but I can't find anything related to DDR4 voltage.

Any advice on what this setting is called or where to find it? I'm on the latest beta BIOS (4.21) with a Ryzen 5950X CPU.

The RAM I'm experimenting with is G.Skill F4-3600C16D-32GVKC, which is DDR4 3600 MHz CL16. It says it needs 1.35 Volts. I tried setting all the RAM timings without changing the voltage (1.2 V presumably) and it didn't POST, so I'm pretty certain I need to up the voltage, if it's going to work at all.

Thanks!
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ThreeDee View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote ThreeDee Quote  Post ReplyReply Direct Link To This Post Posted: 05 Jun 2021 at 4:11pm
The X470D4U only runs at 1.2v on RAM
I run 2 different 2 x 16gb ECC UDIMM kits on mine without issue at 2666 (one kit is rated for 3200, other is 2666).. but they are 1.2v kits'
|Ryzen 5 5900|ASRock X570 Taichi-BIOS 4.60|2x16GB HyperX Predator RGB 3200@3600 1:1 IF|ASRock RX 6700XT|2 x PCIe 4.0 M.2 Drives for OS & Games|850 WTT Seasonic 80+ Titanium PSU|Noctua NH-D15|
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Post Options Post Options   Thanks (0) Thanks(0)   Quote icanhazhax Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jun 2021 at 10:33pm
Thanks ThreeDee!

After a ton of experimenting, I surprisingly got the RAM working at 3600 MHz and 1.2V. I was able to verify the performance using some memory bandwidth tests (sysbench, mbw) and comparing them to performance at 2400 MHz and to another system running at 3200 MHz. dmidecode reports the "Configured Memory Speed" as 3600 MT/s too.

There are two key tricks that you need to know to get the RAM to overclock on this board, which took me 2 days to figure out:

1) In the Memory Overclocking screen in the BIOS, the "Memory Clock Speed" must be set to HALF of what you want it to run at. For 3600 MHz, it must be set to 1800 MHz. Anything above 1900 MHz causes the board not to save the RAM timings, which is what tipped us off to this quirk.

2) Many of the values in the Memory Overclocking screen must be entered in hex! This was not super clear. You'll need to convert the decimal timings to hex.

For our RAM timings, we used the "DRAM Calculator for Ryzen" software to get the correct values. The G.Skill kit above is Hynix CJR/DJR, single rank, so we entered that into the software along with the correct chipset (X470) and clicked "Calculate SAFE". We then converted these values to hex:

RAM Timings (numbers all in hex, except for the memory clock speed):

Memory Clock Speed     1800 MHz
tCL     10
tRCDRD     11
tRCDWR     10
tRP     12
tRAS     20
tRC     34
tRRDS     6
tRRDL     8
tFAW     20
tWTRS     4
tWTRL     C
tWR     18
tRDRD SCL     4
tWRWR SCL     4
tRFC     167
tCWL     10
tRTP     8
tCKE     1
tRDWR     8
tWRRD     1
tWRWR SC     1
tWRWR SD     7
tWRWR DD     7
tRDRD SC     1
tRDRD SD     5
tRDRD DD     5

I hope this helps someone else out there with RAM compatibility on this board.

Thanks!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ThreeDee Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jun 2021 at 12:50am
DDR = Double Data Rate .. ie .. 1800 actual x 2 = 3600.

3600 rated RAM sounds better than 1800 and then explaining how DDR works.

Soo .. when setting fclk ..a.k.a.. Infinity Fabric .. it's set same way as RAM actual speed .. i.e .. matching fclk to 3600 rated RAM is 1800.

It's great that you got it going! ..and thanks for the info!
Desktop AM4 boards are a little easier to setup.. and go to 1.35v on RAM as well.
|Ryzen 5 5900|ASRock X570 Taichi-BIOS 4.60|2x16GB HyperX Predator RGB 3200@3600 1:1 IF|ASRock RX 6700XT|2 x PCIe 4.0 M.2 Drives for OS & Games|850 WTT Seasonic 80+ Titanium PSU|Noctua NH-D15|
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