Question FCLK value doesn't survive sleep mode

[JayGau]

I have a good one for you guys.

I have 2x8 Gb Corsair Vengeance LPX RGB DDR4 3200 C14 that I overclocked to 3733 Mhz at 16-16-16-36. It works very well and it's stable. AIDA gives 53 Gb/s read and a latency of 69 ns. But the problem is that when the computer goes to sleep and wakes up the read is much lower (49 Gb /s) and the latency goes up to 79 ns.

So I took a look at Ryzen Master and realized that the FCLK value that I manually set to be half the memory clock changes when the computer wakes up from sleep mode. It looks like it always resets it to 1800 Mhz whatever I set in the BIOS. So if I put 3733 Mhz and FCLK at 1867 it works just fine until the computer goes to sleep and wakes up. After that it's back to 3733 Mhz and FCLK = 1800 Mhz so the dual mode is turned off and the performances decrease. I tried to put a lower number like FCLK = 1783 Mhz just to see and it also goes back to 1800 Mhz.

Of course if I set 3600 and 1800 the sleep mode has no effect. Same if I put 3200 and 1600.

Anyone has an idea why Windows 10 sleep mode resets my FCLK to a specific number?

ASUS ROG Crosshair VII Hero
AMD Ryzen 3700x
NZXT Kraken X52 cooler
Corsair CMW16GX4M2C3200C14
EVGA RTX 2080 XC Ultra
Samsung 970 EVO Plus - 1TB PCIe NVMe - M.2 Internal SSD

 

[JayGau]

Ok I figured out. It's a motherboard bug introduced in the 2901 BIOS version (sleep mode automatically sets the FCLK to 1800 if the memory clock is equal or above 3600 Mhz). Looks like Asus is still messing up with the memory on their X470 boards. I read that there are a lot of complains about that so maybe Asus will fix the issue in their next update. In the meanwhile I downgraded to 2801 and it works fine.