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Journeyman III

3950X unstable with only 10% increased limits

I recently built system with Ryzen 3950x and MSI MEG x570 Ace. The issue I am having is the stability. If I increase the limits with only 10% - I cannot pass full cycle of prime95 blend test. It freezes or reboots somewhere between 2nd - 8th hour.

Here are the system specs:

Ryzen 3950

MSI x570 Ace, bios v17 (latest)

EK performance 360 water cool kit

2x16GB gskill F4-3200C14D-32GVK (and also tested with other 2x8GB kit)

PSU be quiet dark pro 11 1000w

BIOS settings:

Enable a-xmp,

pbo - advanced, limits - manual - PPT 156W, TDC 105A, EDC 154A.

Other bios settings are on their default/auto values.

This is not supposed to happen I believe or it would make pbo completely useless.. damn only 10% makes it unstable. It does not overheats, I have hwinfo logs during the prime tests and can share the data.

Could I have bad cpu or motherboard? (I exclude the memory because I confirmed the same behaviour with another memory)

Could I do something in order to get stability with at least 10%-20% increased limits?

P.S attached is some hwinfo data from first 2 hours of prime95 with no increase of limits (green) vs 10% increased limits (red).

9 Replies

PBO pushes the CPU to its maximum speed whilst monitoring the limits whereas manually overclocking can push it past the limits and make it unstable.  

There isn't a lot to be gained from overclocking these Ryzen CPU s as the PBO function is very efficient.  



Sorry, this information is not correct.  You two need to read the Ryzen Master (RM) Quick Reference Guide (QRM).  If I run my 3970X on Cinebench for a single core, one core goes to the limit.  PBO is not needed.  Across the top of RM are meters for Temperature, PPT, TDC and EDC.  These limits are always enforced but can be raised (except for temperature) to limits set by the MB vendor.  Again, please see the QRM to do this.   I am glad to try to answer questions - please ask.  Thanks and enjoy, John.


Yes that is correct for single core performance John.

However, for multi core performance, disabling PBO will restrict the maximum speed on my Ryzen 3700X to 3900 MHZ.

Enabling it will allow an all core boost of 4100 MHZ.

As Cinebench is a synthetic benchmark it can be used to benchmark both single and multi core performance individually.

I also get better multi core performance in games with PBO enabled.  




Hi Andy. I also gave PBO try on my Ryzen 3700X and it does something close to 4100 Mhz on a Asrock B350 Pro4 but my single core drops to barely 4.3 Mhz. Without PBO it does 4391 Mhz single core, hovers 3967-3992-4017 in all core at KeyShot

Journeyman III

Hello, i have the same Problem of freezes even without advanced limits. It seem to be a software issue. Do you also have an AMD graphics card?


Hi albiback,

No I have nvidia 1080 ti gpu.


albiback, please right click This PC-Manage-Event Viewer-Windows Log-System.  Or right side click Filter Current Log..., then select Critical box then click OK.  If you get any hits, select one and post the BugcheckCode here.  Thanks and enjoy, John.

Journeyman III

I have a little update to my instability problem.

I tried older bios v15 (agesa - it didnt fix my issue.

Anothet thing that I noticed - last two times during prime95 blend the pc did not restart, but got rounding error in prime95.

Both times the dead tread was from same core 12 (hwinfo numbers them from 0-31). First time it was on fft size 18k, second was on fft size 20k.

But the problem is that I cannot repeat. I mean - if I manually run prime with 18k or 20k it works without crashing (running more than a hour same fft size). I think that during the blend test the workers are not synced and it happens that one thread is working on large fft size, another is working on small fft size. And this coincidence leads to instability and core 12 crashing (working on small fft size).

So most probably the problem is in the cpu and may be I will have to RMA.

Journeyman III

And final update, if anybody cares.

Returned everything. Got another 3950x and msi x570 unify. It is running very stable with +30% raised limits.