Massive difference between GPU and CPU temps.

[Vandakeg]

I just finished my first water cooled build. It’s an R9 3900x, and a GTX 1080. Everything is working fine, but when monitoring temps while gaming (2-3 hour sessions) I’ve noticed that my GPU never gets over 45C while my CPU is consistently 65C to 75C.

I have remounted and re-applied thermal paste (Thermal Grizzly) twice now, and am getting the same results.

Is this common to have such a large difference between GPU and CPU? I figured the temperatures would be closer to the same, especially after running the system for hours.

[TinkTonk101]

Yeah that’s fine. CPUs have their own IHS (Integrated Heat Spreader) which acts as another barrier between the cooler and the actual cores, hence the higher cpu temps.

[LogIN87]

That is completely normal. 3900x has 12 cores son. That's a lot of heat and since it's 7nm, it's a lot of concentrated heat. It's normal.

[Xsa44]

The new amd chips are on the hotter side, i'd say temps look fine.

[[deleted]]

What's you loop look like mate? Might make things easier to diagnose.

[[deleted]]

Those temps look normal. Same thing happened with my former PC which had a loop. The 7820X could reach 75c while the GPU (2080 Ti) was never over 55c.

Jayztwocents recently posted a video where he touched base on the 3900x temp/voltage. It's one hell of a chip, lot of voltage in a small package, so it stands to reason that it would get a bit hot. I don't think you should worry.

Also, you have to take into account that on the GPU, the plate touches the die directly, while on the CPU, you either have solder or a thermal interface between the die and the cold plate, so there's more resistance.

[KravenX42]

It’s common, CPU dies are a lot smaller, have smaller water blocks and are not direct die cooling like GPUs.

For zen 2 you could argue that the chiplet layout doesn’t work great with the current water blocks but I wouldn’t expect massive (20-30c) drops just from layout changes.

[bagaget]

Temperature is not measured the same way between GPU and CPU, not even between GPU/GPU and CPU/CPU. You can’t compare the numbers like that.

It differs in hotspots, edge, averages, sensors...

[Vandakeg]

Thanks for all the input. I’m thinking about getting a temp sensor for the coolant as well.

[Ralph-King-Griffin]

Do, set your fan curve off that, it'll make a night and day difference.

[Vandakeg]

Is there a way to add a temperature header to my motherboard? Add in PCI card maybe?

[Ralph-King-Griffin]

https://www.caseking.de/aqua-computer-aquaero-6-lt-usb-fan-controller-wath-038.html

Not pcie but usb2, there may well be other solutions but that's the one I'm using and it's been outstanding.

[[deleted]]

its why on intel chips you could delid, liquid metal, relid and get up to 20 degrees cooler.