5900X Low All Core Boost

Ginger Penguin · January 18, 2021

Hi all,

I've got myself a 5900X and it's just not performing as well as I had expected it to. Doing a stress test at stock, I'm only getting about a 4.15GHz all core boost. And with PBO/Auto OC, I'm getting 4.22-4.25 but, say for instance in a 10min Cinebench run, this will degrade slowly down to about 4.15 over time but it doesn't seem to be thermal throttling. Temps seem to be around 75 degrees the whole time. I've been seeing people getting 4.5GHz all core boosts which would be very nice to have. I followed an undervolting guide where the person presenting the video was able to get a value of 30 easily on his Zen 3 CPUs but only a 12 on the 5950X. I wasn't even able to get it to boot at 30. I thought I had it stable at 12 but I was getting random crashes so I kept dialling it back until I gave up at 8 and just returned it back to stock as the results I was getting were no better than with PBO/Auto OC.

I've also had issues trying to get memory to overclock properly. Trying to set the Infinity Fabric to 1900 and I get a no POST. I thought that practially everyone was able to get 1900 and it was 2000 that was pretty much unattainable. It doesn't seem to be a memory issue as I actually got the memory running fine at 3800 but hadn't realised that setting the Infinity Fabric to Auto didn't actually change it from stock. Trying to do practically any timing optimisations seems to cause it to crash pretty quick as well.

I don't know if all of these issues could be related to CPU or maybe it's the motherboard/BIOS. I had a weird issue when installing the CPU that it would boot into the OS fine but pressing the BIOS key would just give me a black screen and a POST code of A9 unless there was something plugged in to SATA3_5. Even if 5&6 were disabled by having an M.2 drive installed in the slot that shares their lanes. I didn't have this issue with a 3700X that I used to do the BIOS update or with an Athlon 220GE that I used to try and do the BIOS update in the first place (was able to boot but wouldn't update the BIOS). I've thought about waiting until there's the next BIOS revision from Asrock to see if there's anything they've done to improve performance. With any luck it shouldn't be too far away.

Anything else I can try to work out where the problem lies?

obogobo · February 16, 2021

Hi! Wondering if you ever solved this? I'm having the same issue and started a thread with some info from other sources if you'd like to come chat!
https://www.reddit.com/r/Amd/comments/llet7x/the_zen3_1900_fclk_hole_issue/