Advice needed, memory issue with 64GB (4x16GB)

[Stim]

Hi folks,

I'm after a bit of advice with my new build.

Initially I ran the following:

• Asus Crosshair VIII Hero
• AMD 3900x
• Team Group 8Pack Edition 32GB (2x16GB) DDR4 PC4-28800C16 3600MHz Dual Channel Kit

I did a reasonable amount of overclocking on the processor on the above setup and settled at a happy level - then came along a purchase of another set of RAM (identical 8Pack set to the above, making the total 64GB across 4 DIMMs.)

Unfortunately at this point booting became sporadic, and more often than not the PC wouldn't POST due to reported 'stability issues' - forcing me back into BIOS to rectify my sins. The issue here is that even using the DOCP/XMP profile with stock CPU clock, 90% of the time I get forced back into the BIOS with the dreaded 3 reboots. On the odd occasion, it does seem to go into Windows. At that point all appears fine, no issues. Stressed tested and it seems stable.

I tried multiple OC settings and the DOCP/XMP settings (using the supported RAM speeds) but no avail.

Now it took me a while to "clock on" (sorry about the pun) as to what the problem was as I initially had intermittent issues, but I've narrowed it down to having the four sticks of RAM in the board, rather than two.

Running with two sticks (either set) gives me no issues whatsoever - I can happily overclock the RAM to higher settings than the 3600Mhz stated, too.

Running with four brings me back to square one. At DOCP/XMP settings, struggling to boot. I manage to get into Windows using 'Auto' for the RAM speed, but this puts me at a meager 2400Mhz. Not something I'm happy with given that it's top grade RAM.

I've also tried different versions of BIOS, including the latest (2206 - August 2020) and one of the earlier revisions with no joy.

Is there a voltage setting I need to increase somewhere in support of the additional DIMMs? I've tried increasing the RAM voltage itself up to 1.45v @ 3600Mhz but still hit the boot loop.

Any advice appreciated.

 

[MissChief]

Either a dodgy stick or a dodgy slot. Although it's not recommended try a single stick on all four slots. Then try another stick. It's likely one of the slots you're now using though so this should narrow it down.

 

[Joxeon]

Try upping the soc voltage to 1.15

 

[Stim]

Thanks for the quick responses, guys. Appreciate it given the hour.

I jumped on the unofficial discord and a few of you helped me out here.

Tried multiple seatings with the RAM, cleared the CMOS (again)

To cut a long story short, I'm now back in Windows at DOCP/XMP settings. Possibly either a seating issue or an odd BIOS setting I'd had - not sure which.

I've saved the BIOS profile - next step is the overclocking with 4 sticks (if it's not broken, try to make it better )

I'll try not to revisit...!

Thanks for the help.

 

[bremen1874]

Running that much memory pushes the processor's memory controller much harder. Possibly having to wind settings back is an accepted compromise.

 

[GregI]

I'd look into termination settings with help from DRAM Calc.

Settings with 2 DIMMS:

Settings with 4 DIMMS:

Most likely your board is setting bad termination settings. I'd take a punt with changing RTT_NOM

 

[Stim]

Thanks, this is really helpful stuff.

I had a quick go at raising the speed last night but anything past the rated 3600 didn't boot. I'll try looking at the dram calc to see if I can squeeze anything more out of the kit.