Your thermal pads might be a little fat making a little loose on die contact. Hotspot delta looks really good. Either that or not enough flow from pump or need more rad

My 4090 on ambient waterblock will get to 51-52c at 450 watts but as soon as load is off it drops down to usualy 24-28c depending on my small room temp which can get pretty warm sometimes lol

 

I removed the water block, with the water block I got perfect temps, lower 40 degrees under full load

Now I went back to stock air cooler (cause I want to sell it) but I used 1.5mm on the VRAM, very soft pads (the Aairhut) but I am not sure if them not compressing properly is causing this issue or maybe its not an issue at all?

Really not sure about this... and whether to reopen and reassemble it, a buyer might be frustrated having these temps

@Gamerman what thermal pads do you use?

 

did you replace the thermal pads with the same thickness that came with the block?

some parts can use thicker pads than others so you have to double check.

also i havent had a chance to try myself yet but ptm7950 requires break in a few cycles supposedly

 

I used 1.5 instead of 1.25 because I cant purchase 1.25 anywhere

Is there a method how to find out if it is fine to use the thicker pads?

 

Use Gelid GP-Extreme 1.5mm thermal pads. They are super soft and squishy and will compress fully to allow full contact with your GPU core. Plus they perform really well, the go-to pads a long time now.

DON'T use the Ultimate, they are quite hard and don't compress, and you'll lose contact with the GPU core.

Oh, Kritical pads are really good as well.

And I just checked, Kritical has 1.25mm pads.

 

I just used cheapy 12kw owltree pads off amazon. They are pretty soft also

 

It's really interesting I replaced the thermal pads on VRM etc. with Arctic TP-3, put thermal putty on the VRAM, and some (probably fake) PTM7950 on the GPU itself

Now I get these values
furmark (after 10 minutes, avg): GPU 67 / MemJ 66 / Hot Spot 77 / Power 560 watts
cyberpunk (also after 10 minutes): GPU 60 / MemJ 67 / Hot Spot 69 / Power 426 watts

Yesterday in the evening the values were much worse, GPU in the seventies, hotspot in the eighties, but today it seems to be better... I really double-checked, the average power consumption definitely is what it was on my first tests, not sure why that is

And also not sure why it's generally so much better now, but I'm happy with it... Maybe it's because I put so much thermal putty that it probably went a bit further on the board than just the VRAM

 

You took the blue thermal pad plastic off, right?

 

Of course I did