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Look at my PCB... where are my VRMs?

martinoheat

martinoheat

martinoheat

Associate
Joined
2 Aug 2012
Posts
335
Location
Leeds
I fitted an Arctic Accelero Xtreme to my AMD 7950, and was VERY impressed with the results.

So, when i bought a HIS R9 280x Turbo to crossfire with the 7950, i decided to fit one to that too.... and the core cooling is GREAT! Only the VRMs don't seem to be cooled at all! - they still reach 90 - 110 degrees C!

Whereas the VRMs on my 7950 don't go above 60 degrees.

The VRMs on the R9 280x are quite different to the ones on my 7950 - they are very flat.

Here is a picture of my R9 280x PCB.
Here is a picture of where i have fitted the heatsinks.

Have i made a glaring mistake in fitting the heatsinks?

If i've put them in the wrong place, please could you mark on the picture where i should have fitted them, and reupload it?

Thanks again! You guys have been SO helpful with troubleshooting my problems :)
 
Black things are chokes the silver flat things that now have the heatsinks on are VRM's.
 
martinoheat said:
I fitted an Arctic Accelero Xtreme to my AMD 7950, and was VERY impressed with the results.

So, when i bought a HIS R9 280x Turbo to crossfire with the 7950, i decided to fit one to that too.... and the core cooling is GREAT! Only the VRMs don't seem to be cooled at all! - they still reach 90 - 110 degrees C!

Whereas the VRMs on my 7950 don't go above 60 degrees.

The VRMs on the R9 280x are quite different to the ones on my 7950 - they are very flat.

Here is a picture of my R9 280x PCB.
Here is a picture of where i have fitted the heatsinks.

Have i made a glaring mistake in fitting the heatsinks?

If i've put them in the wrong place, please could you mark on the picture where i should have fitted them, and reupload it?

Thanks again! You guys have been SO helpful with troubleshooting my problems :)
Click to expand...

No its right, newer GPU's use those flat VRMs, i have one (Tahiti LE) it comes with a similar VRM HS to the one your putting on it. see pix

As it is out of the box.



And with the VRM HS off.



I don't know why your VRMs are getting so hot, mine don't get much past 70c, ever, even with a 1200Mhz overclock.
 
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You tend not to see any cooling on the chokes so unless their's natural air flow somehow blowing over them then I guess then don't really need it, you can also look around the cpu socket on a modern board and see them poking their head out from under the VRM heatsink.
 
Now this looks like a great idea :o - really like the look of the heat-sinked vrms - cool pics :)
 
Does anyone know what the sprung loaded bracket around the GPU on the back of AMD cards does as when fitting waterblocks you don't use this.
 
idk I think the bracket supports the pcb,stocks it from twisting/cracking

EDIT: esp with a spinning fan,it would vibrate things I guess
 
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Rroff said:
Which is actually the temperature measured component? I assume the MOSFETs rather than the chokes but I'm pretty rusty on my electronics.

EDIT: Googled my own answer the MOSFETs are sensitive to overheating.

EDIT2: This is a good read on the subject even though its about motherboards - similiar applies http://www.overclock.net/t/943109/about-vrms-mosfets-motherboard-safety-with-125w-tdp-processors#
Click to expand...

On the image I posted, have I stuck the heatsinks to the MOSFETs, so I don't see why their temperatures are still so high.

Thanks for the info, I tried to read through it, and I understood some of it, but most went over my head. Lol







humbug said:
No its right, newer GPU's use those flat VRMs, i have one (Tahiti LE) it comes with a similar VRM HS to the one your putting on it. see pix

I don't know why your VRMs are getting so hot, mine don't get much past 70c, ever, even with a 1200Mhz overclock.
Click to expand...

What kind of conductive material is there under the heatsink on your VRMs? - is it paste or sticky back pads? - I used the thermal adhesive supplied with the cooler, but I see that the stock heatsink (a plate that covers the whole PCB) uses sticky pads.
Is it possible pads would be better than thermal adhesive?
 
martinoheat said:
What kind of conductive material is there under the heatsink on your VRMs? - is it paste or sticky back pads? - I used the thermal adhesive supplied with the cooler, but I see that the stock heatsink (a plate that covers the whole PCB) uses sticky pads.
Is it possible pads would be better than thermal adhesive?
Click to expand...

Its a sticky pad strip, it might be better for contact, if the HS is not completely flush Thermal Compound might not have any contact with it, Thermal pads are thick so they fill in the gaps.
 
i'm going to return the 7970 cooler (even though on the box it says compatible with 280x), and get the 280x-specific cooler, with the backside VRM heatsink, and see how i get on with that.

i'll report back my findings.
 
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