ryzen 5900x Ryzen 5900x idle temp pretty high

[Mambans]

Hello, a few months ago I upgraded to an Amd 5900x + EK-Quantum Momentum ROG Crosshair VIII Hero and Rtx 3800 with full custom water cooling (2 rads, one intake at the bottom and exhaust at the top).
But I've noticed my temp on my Ryzen 5900x fluctuates a lot while idle, from 55/60 up to 75. And while running Cinebench it still only stays around 70-75 and the score seems O.K.
All while my GPU temp stays around 30-45 while ~idle.
My ambient room temp is pretty high, around 23-26.
Water temp is around 35-42c.

I'm wondering if anyone know why my CPU idle temp (55-70) is so high?
Did I not mount the CPU block correctly?
Is it the loop configuration?

Would appreciate any tips.

[AnonymousGuy]

I would go through and retighten the monoblock screws.  What could be happening is the package is expanding under load just enough to maintain good enough contact to handle the load heat and when it's idling it becomes a poor mount.

 

Also this is one of two reasons why I hate monoblocks.  Cause now you have to remove the whole motherboard to even troubleshoot it and VRM's don't need watercooling nowadays.

[Bad5ector]

It is either mounting pressure or perhaps thermal paste application. I know I had to reseat my waterblock several times to get the temps down where I wanted them. I have basically same setup minus monoblock and I idle around 33-45 depending on what is being done in the background. Cinebench I sit around 61-65, but I haven't let it sit for a while to let the heat soak, usually just a few runs in a row. But figured I'd give you those numbers for some sort of reference.

[Mambans]

Hi, thanks for the tips. Those were kinda what I was thinking but were just to lazy/annoyed to try (monoblocks...). I'll try remount the block the double check the thermal paste. Thx!

@Bad5ector Your temp seems much more reasonably, do you have water-cooling too?

[Bad5ector]

7 minutes ago, Mambans said:

Your temp seems much more reasonably, do you have water-cooling too?

[Mambans]

Ah, same loop config it seems too. I must have a bad mount then ;/ Thanks!
Just curious, you don't happened to know your waters temperature?

[Bad5ector]

2 hours ago, Mambans said:

Just curious, you don't happened to know your waters temperature?

The water-in temp under load is usually around 43c and 41c water-out. That's roughly after a long gaming session, so the loop has definitely reached equilibrium. 

[HM-2]

Monoblocks seem to have issues with this sort of thing. Far more variables from a clearance and alignment perspective than traditional CPU blocks.

[Mambans]

3 hours ago, Bad5ector said:

The water-in temp under load is usually around 43c and 41c water-out. That's roughly after a long gaming session, so the loop has definitely reached equilibrium. 

Ah oke, thanks!

[Mambans]

1 hour ago, HM-2 said:

Monoblocks seem to have issues with this sort of thing. Far more variables from a clearance and alignment perspective than traditional CPU blocks.

Ah, makes sense. Do you thinkif it might help trying to remount the block, in hope for a better fit?

[HM-2]

32 minutes ago, Mambans said:

Ah, makes sense. Do you thinkif it might help trying to remount the block, in hope for a better fit?

That would be my suggestion, plus double checking any thermal pads.

[fonzz1e]

is your 5900x running with pbo on? 

 

 

[Mambans]

6 hours ago, fonzz1e said:

is your 5900x running with pbo on? 

 

 

I think so, both in ryzen master and bios.

[Mambans]

After remounting and re-pasting the block cpu monoblock the temps seems to have gone down a bit, but not as much as I'd hoped. It still idles around 52-55c with water temp at 36.

[fonzz1e]

27 minutes ago, Mambans said:

After remounting and re-pasting the block cpu monoblock the temps seems to have gone down a bit, but not as much as I'd hoped. It still idles around 52-55c with water temp at 36.

u can actually find its max temps with 30 mins run of prime95 small fft or cinebench loop

[Mambans]

3 hours ago, fonzz1e said:

u can actually find its max temps with 30 mins run of prime95 small fft or cinebench loop

I'll try that out.
How do you run cinebench in a loop? Is it possible thought the UI or just the command line? Always wondered.

After running Prime95 for about 30min I am around 75c with PDO and if I disabled PDO i drop down about 10c to ~ 65c.
But PDO disabled or enabled have no effect on cinebench, both give me a score around 7500.

I also noticed that the voltage is around 1.3-1450  while idle.

 

[fonzz1e]

looks good for stress temps, coolant temps during stress?

 

u can also set negative curve optimizer in your pbo settings, should improve your load temps

 

i guess idle temps can't really do much about it since you already tried remounting it