Idle temps seem higher than expected, but do not raise under load?

[Elverion]

Relevant parts:

Ryzen 3950x

NZXT Kraken X73 360mm AIO (yes, I know it's overkill for just a CPU, but it was the only thing available at the time that wasn't ridiculously overpriced)

Noctua thermal paste

 

Under idle, CPU temps bounce between ~38-55C, and liquid temp stays at a constant 28C. Under a stress-test load or while gaming, temps stay constant at exactly 51C but liquid temp can raise 1-2°; fans and pump seem completely unphased. and barely change. This is rather odd and I cannot make sense of this and it leaves me with a lot of questions. Why is the idle temp so jittery while load temp is so constant? Why is the load temp (sometimes) lower than the idle temp, despite no apparent change in cooling capacity (remember, fans and pump stay near constant)? Why is it idling relatively high to begin with?

 

At first I thought it was because of an air bubble trapped in the block or something. I tried moving the radiator around to help remove any stuck bubbles that could be there and saw no change. Then I tried removing the block and reapplying thermal paste just in case it wasn't making good contact and again saw no change. Neither of those should result in the behavior I'm seeing, but who knows.

 

Since the load temps are good, I'm not too worried about it. Should I be?

[Jae Tee]

Are you sure that you have the fan and pump headers in the correct location, and that the fan and pump controls are properly set up?

[Elverion]

1 minute ago, Jae Tee said:

Are you sure that you have the fan and pump headers in the correct location, and that the fan and pump controls are properly set up?

Pretty sure, yes. I have the AIO plugged into the AIO slot on the motherboard, and the radiator fans are plugged into the CPU fan header.

[Mateyyy]

Sounds like normal behaviour. Idle temps tend to jump around more because of the aggressive boosting Zen 2 does for even little background processes.

[Jae Tee]

I guess if your looking to cool it further you'll need to look in to your bios fan settings. If those are not getting the results your expecting you may have a bad thermal paste application.

[Elverion]

Just now, Jae Tee said:

I guess if your looking to cool it further you'll need to look in to your bios fan settings. If those are not getting the results your expecting you may have a bad thermal paste application.

Honestly, this is my first experience with water cooling. The last time I built a computer, water cooling was still too expensive for a custom loop and AIOs were still very new and not yet proven to be reliable. If those numbers seem perfectly normal to you guys with more experience, then I'm totally fine with it. I had just expected lower idle temps.

I think it could perhaps also be that the lid of the CPU isn't perfectly flat so I could try lapping it, but at the same time... I don't want to go voiding the warranty on a new 3950x just yet.

[Jae Tee]

8 minutes ago, Elverion said:

perhaps also be that the lid of the CPU isn't perfectly flat so I could try lapping it

Nah as you said the temps don't look bad for regular use so this kind of stuff isn't necessary, unless you really wan't to or if you plan on OCing or some thing like that.

[ChrisZH]

13 hours ago, Elverion said:

Relevant parts:

Ryzen 3950x

NZXT Kraken X73 360mm AIO (yes, I know it's overkill for just a CPU, but it was the only thing available at the time that wasn't ridiculously overpriced)

Noctua thermal paste

 

Under idle, CPU temps bounce between ~38-55C, and liquid temp stays at a constant 28C. Under a stress-test load or while gaming, temps stay constant at exactly 51C but liquid temp can raise 1-2°; fans and pump seem completely unphased. and barely change. This is rather odd and I cannot make sense of this and it leaves me with a lot of questions. Why is the idle temp so jittery while load temp is so constant? Why is the load temp (sometimes) lower than the idle temp, despite no apparent change in cooling capacity (remember, fans and pump stay near constant)? Why is it idling relatively high to begin with?

 

At first I thought it was because of an air bubble trapped in the block or something. I tried moving the radiator around to help remove any stuck bubbles that could be there and saw no change. Then I tried removing the block and reapplying thermal paste just in case it wasn't making good contact and again saw no change. Neither of those should result in the behavior I'm seeing, but who knows.

 

Since the load temps are good, I'm not too worried about it. Should I be?

Ryzen 3000 CPUs are not as cool as you think. My CPU is usually in the 40s idle on a custom loop (3800x). Have you checked the voltage your sending the CPU? The stock voltages are crazy high. Sometime 1.5v, if it's high try lowering to like 1.375 or 1.35v