PC Building

[Merman12]

Hello everyone. Recently I built myself a custom gaming pc. And as the title says, when I turn xmp/expo on in my bios the pc won’t post at all. 

my specs are as listed.

gigabyte b650 x ax gaming motherboard

ryzen 9 7950x

asus rog 4070 ti super 

128 gb ddr5 g.skill trident z5 rgb 6400 mhz 

Nzxt kraken elite 360 rgb aio 

Corsair rm850x gold psu 

I’m well aware the issues with running all 4 ram slots, and how it’s a bit unstable. But the mobo is advertised as being capable of 8000 mhz. But I can’t get it past 3600 mhz in bios. If anyone has some insight and can help. Please do so 

[BigAl01]

I would take two sticks of RAM out and see if the motherboard can support EXPO for the remaining two sticks of RAM.  I would also look for a BIOS update for your motherboard and install that (maybe while only running two sticks of RAM) to see if does the trick.  Lastly, is your RAM listed as being compatible with your motherboard?

[Merman12]

Thank you both for the reply, I’ll be trying this in my next day off of work. I did do the most recent bios update for my mobo not too long ago. And I just checked last night about my ram. And it is a supported ram kit for this mobo. I also couldn’t find anywhere in the bios where I can set my own custom profile for expo. I wanna try getting it close to 6000 mhz if possible 

[FunkZ]

As @BigAl01 suggests, you will likely have better luck running at 6400 with only 2 DIMMs installed.

The motherboard may be built to handle up to 8000MT/s but it's the IMC in the 7950X that has to address that memory, and when you use 4 DIMMs it can't hit the higher speeds. Also the motherboard may be advertising higher memory speeds supported in upcoming Zen5 9000-series processors yet to be released.

The only 32GB modules I found on your board QVL supported in x4 DIMM configuration are these 4800MT/s Crucial.

https://www.gigabyte.com/Motherboard/B650-GAMING-X-AX-rev-10-11-12/support#support-memsup

https://www.amd.com/en/products/processors/desktops/ryzen/7000-series/amd-ryzen-9-7950x.html

[mengelag]

Does your MB Bios have a "try it" section for trying different RAM speeds and timings? Could try a few of those to see if a different speed and fabric clock work or try the second EXPO profile and see if that works because the second profile will generally load a more comprehensive set of settings. Just an idea...

[johnnyenglish]

@FunkZ already said it

You won't get those speeds. Sorry, too much on the IMC

If you like, try Memory Context Restore disabled after enabling EXPO and lower speeds to something like 4800/5200 but with 128gb you'll get some delay from memory training every time it boots.

One more thing, if its pure gaming you seek, then memory speed matters most than memory capacity unless its a niche very demanding game.