Question Bad 5900x or not enough mobo?

[hokenpoke]

So I just swapped out a 5900x for a 3700x in my productivity machine and it booted up just fine. Life was good until . . . I fired up Cinebench to see what I was getting in terms of performance boost and it instantly black-screened; this in a way I had never seen before - holding down the power button would not recycle it. I had to switch off at the PSU to get it to fire up.

I did this a couple more times with Ryzen Master open and noticed that just as I kicked off something stressy, the PPT and EDC maxed out and a black screen ensued. This reminded me that I had heard that 5000 series CPUs would be undervolted so I initially did a manual offset of 100mV and tried again. This did the trick so I experimented with using PBO/Curve Optimizer starting at -15 and noting that Cinebench performance went up and temps went down the more negative the CO. I stopped at -25 because the gains were flattening out and it was working fine. Which is where things are right now.

But . . . I am wondering if I have a borderline faulty CPU or is it that the mobo - a MSI B450 Gaming Pro Carbon AC - doesn't have the oomph for the 5900x. I had understood that it should be OK and that this mobo has a decent VRM but maybe not?

Is there anything I can do to see where the problem lies? I see no reason to not continue undervolting and I'm not above keeping $200 in my pocket, but I would like to know if I need to either seek recourse on the CPU or shell out the $200 for a beefier B550 or so. Any thoughts would help.

 

[punkncat]

I note the 5900X in the compatibility list, so that is giving the nod that it should work fine.

My concern would be what manner of cooling you are using on this build? For instance, if you are water cooling there may not be enough airflow over the VRM heatsinks and it could be pulling a thermal shutdown.

 

[hokenpoke]

I am water cooling - rad is front mounted with fans on the inside in pull config. The case is pretty porous - Fractal Meshify and I have 2x120 exhaust fans just above the VRM along with a 120 exhaust in the back. So . . . I think it's pretty good.

Is there a way to set up some sort of monitor that would log temps and volts?

 

[punkncat]

HWMONITOR should register everything you would need to watch to get an idea of this.

 

[hokenpoke]

Thanks - I ran HWInfo on a Cinebench session that ended up black-screening. I don't see anything crazy in the log though the VR temp is definitely rising: https://docs.google.com/spreadsheets/d/1dBWQERRJq_z6gCglPWeaaSTKRoaESEHQ9xumakL86GQ/edit?usp=sharing

 

[hokenpoke]

OK - I kept dialing back the Curve Optimizer until I got a full run of R23 at -17 giving a respectable 21035. The VRM seemed to keep up fine with the temp stabilizing at 74 which seems high but not too bad - I will be looking for next mobo with a beefier VRM sooner rather than later.

All of this still leaves me with the impression that the CPU is flaky - it won't handle any load at out of the box settings and while I will certainly be undervolting because it just makes sense to do, it still seems like it should work with no UV.

Anyone want to convince me otherwise?

 

[mdd1963]

I'd suspect the mainboard before the CPU, but then, whichever one picked to swap first...it'll undoubtedly be the other! (Unless you picked it first!)