Heatsinks on GPU Backplate

PieEater · 9 Jan 2025 at 19:19

I've repasted and repadded my 6800XT and was wondering if anyone has ever stuck some heatsinks on their GPU backplate above the GPU and memory modules where the thermal pads are and if so was there any appreciable difference in temps.

/Edit: The rainforest place has some active and passive backplate coolers, but I can't really find any positive user feedback.

Bubo · 10 Jan 2025 at 08:16

What I've done in the past with passive backplates I've put on as part of a water cooling setup is just put an 80mm fane above the hot areas with some standoff legs to raise it above the plate, it basically just sits on top of the card. I've no before and after temperatures but common sense says it will be doing something, assuming the backplate is actually in contact with the back of the card via heat pads. I have considered adding those copper ram sinks to enhance this even more but never got round to it. If you added the sinks on their own to your card then I think it would be safe to safe there would be some heat transfer, but would defo be enhanced with some local air flow on to the sinks as per the close fan idea. The only thing to consider beyond this is whether the sinks are going to leave any residue on the plate which you either can't get off, or it somehow leaves an indelible mark, and as such might reduce the sell on value.

Rob_B · 10 Jan 2025 at 08:26

Is the backplate actually metal and thermally connected to the board?

PieEater · 10 Jan 2025 at 09:28

Bubo said:
What I've done in the past with passive backplates I've put on as part of a water cooling setup is just put an 80mm fane above the hot areas with some standoff legs to raise it above the plate, it basically just sits on top of the card. I've no before and after temperatures but common sense says it will be doing something, assuming the backplate is actually in contact with the back of the card via heat pads. I have considered adding those copper ram sinks to enhance this even more but never got round to it. If you added the sinks on their own to your card then I think it would be safe to safe there would be some heat transfer, but would defo be enhanced with some local air flow on to the sinks as per the close fan idea. The only thing to consider beyond this is whether the sinks are going to leave any residue on the plate which you either can't get off, or it somehow leaves an indelible mark, and as such might reduce the sell on value.

Thanks for the idea, I have a spare 92mm fan and will run some tests, what I don't want to happen though for heated to get blown against the side of the case so it gets recirculated to the main GPU cooler as this will defeat the object, so was thinking a large passive heatsink would be better in this respect.

PieEater · 10 Jan 2025 at 09:31

Rob_B said:
Is the backplate actually metal and thermally connected to the board?

Yes and yes, the backplate gets pretty toasty during gaming so there is definitely good thermal conductivity to it, I'll put a thermal sensor on it when I run the tests with the fan on top.

Bubo · 10 Jan 2025 at 09:35

How hot does the backplate feel by the way?

edit: nevermind, answered above.

A bare heatsink would work to some extent, but obviously depends how much general air flow there is. A close fan would work wonders though. As I say, if you are going to be using thermal paste I would lay a fairly confidant bet this would leave a tarnish mark on the plate, so be aware of that. An adhesive pad might not leave as much of a mark, but it is still something to be aware of, if it matters to you.

PieEater · 10 Jan 2025 at 10:24

Bubo said:
How hot does the backplate feel by the way?

edit: nevermind, answered above.

A bare heatsink would work to some extent, but obviously depends how much general air flow there is. A close fan would work wonders though. As I say, if you are going to be using thermal paste I would lay a fairly confidant bet this would leave a tarnish mark on the plate, so be aware of that. An adhesive pad might not leave as much of a mark, but it is still something to be aware of, if it matters to you.

Thanks - I've just run a quick test and the backplate gets to 55c above the GPU core. If I got a heatsink I was planning on getting a thermal pad to go under it and just putting a dab of adhesive at the corners and in the centre edge with some weight on it so it should stick with good contact and be fairly easy to remove and clean if necessary. Airflow isn't an isssue, I've got 4 140mm intakes and 4 140mm exhausts.

Rob_B · 10 Jan 2025 at 10:25

PieEater said:
Thanks for the idea, I have a spare 92mm fan and will run some tests, what I don't want to happen though for heated to get blown against the side of the case so it gets recirculated to the main GPU cooler as this will defeat the object, so was thinking a large passive heatsink would be better in this respect.

More heatsink won't be likely to help that much, you need to remove the heat not just add more mass to absorb it. Eventually, and quite quickly it will become as hot as the backplate and so the temps will stabilise. Ok, maybe it gives your airflow a little more time to remove the heat but I can't imagine it's a big difference.
If you're adding a flat piece of metal (with a few small fins) to a flat piece of metal just how much surface area have you added? Personally I'd go with airflow directed at the backplate if possible, you could test the difference.

Bubo · 10 Jan 2025 at 11:15

PieEater said:
thermal pad to go under it and just putting a dab of adhesive at the corners and in the centre edge with some weight on it so it should stick with good contact and be fairly easy to remove and clean if necessary. Airflow isn't an isssue, I've got 4 140mm intakes and 4 140mm exhausts.

Maybe use a square of aluminium tape to be the layer between the backplate and the sink, then you can use thermal paste on the sink to your hearts content. I assume the adhesive on the tape would come off with some acetone when needed. Still going to advocate for a fan on the sink though, it does need to be forced convection close the the sink for this to work to its best. It will certainly look funky though if you are at all bothered about the looks.

Minstadave · 10 Jan 2025 at 11:20

I was planning to do something similar to my 3090FE, my memory hits max temp and the back plate is very hot so was going to stick a heatsink directly to the backplate to add some surface area.

PieEater · 10 Jan 2025 at 16:36

After a bit of playing around with a 92mm fan the best results obtained dropped ~2c from all temps (backplate / GPU / memory / VRM) which is a bit disappointing. But I have a big airy case (Fractal Meshify 2 XL) with a decent amount of airflow including a 140mm exhaust a couple of inches away from the backplate which I'm guessing will be helping. So for now I'm not going to bother but it's been an interesting experiment.

PieEater · 10 Jan 2025 at 16:44

Minstadave said:
I was planning to do something similar to my 3090FE, my memory hits max temp and the back plate is very hot so was going to stick a heatsink directly to the backplate to add some surface area.

If you check the rainforest site for GPU Backplate they all seem to mention the 30x0 cards so I'm guessing this is a common problem. There's a fairly decent looking active one with dual 70mm fans for £33 which is probably what I'd go for if I decided to fir a cooler though it doesn't come with a thermal pad like some of the others so you'd potentially have to factor that in.

pastymuncher · 10 Jan 2025 at 16:52

Back when I was watercooling I had a Gigabyte RTX3070 Vision OC that had a metal backplate. When I took the card apart I was surprised that the backplate didn't serve any purpose aside from aesthetics. I changed this by putting a appropriate sized piece of thermal pad over the rear of the cpu die, rear of the vrm's and the rear of the memory chips. It actually worked as the backplate got quite warm and with the front 200mm case fan blowing across it dropped core, memory and verm temps by a few degrees so was well worth trying.

Minstadave · 10 Jan 2025 at 16:56

PieEater said:
If you check the rainforest site for GPU Backplate they all seem to mention the 30x0 cards so I'm guessing this is a common problem. There's a fairly decent looking active one with dual 70mm fans for £33 which is probably what I'd go for if I decided to fir a cooler though it doesn't come with a thermal pad like some of the others so you'd potentially have to factor that in.

Yeah it was a big problem back when everyone was mining. I'm pretty sure the 3090FE has pads for the memory as it gets very hot, there's just no surface area to the backplate and not much airflow in that area when using an AIO.

I'm likely to upgrade soon so I'll probably just slap some passive sinks on the backplate and sort case airflow a little better.

PieEater · 26 Jan 2025 at 21:12

So this is what I've ended up with, an aluminium heatsink (150 x 93 x 15mm) sat on top of a self adhesive 1mm thermal pad, held in place with 3 zip ties with a 92mm PWM fan controlled by a thermal sensor on the GPU blowing air over it to be picked up by the exhaust. I have an Asus GPU holder supporting it (the aluminium heatsink is surprisingly heavy). Cost of heatsink, thermal pad and fan came to just under £30.

10 Runs of 3DMark Stress Test	Before	After
GPU Temp	75.4c	70.8c
Memory Temp	60c	58c
Hotspot	106c	91.9c

pastymuncher · 27 Jan 2025 at 14:58

That's a beast of a heatsink and knocking 14.1 degrees C off the hotspot looks to have been well worth doing.

Brizzles · 27 Jan 2025 at 16:41

Would be interesting to see the difference using just the fan makes.

PieEater · 27 Jan 2025 at 17:07

Brizzles said:
Would be interesting to see the difference using just the fan makes.

I tried a fan in the orientation it is now, also with it sat on spacers blowing down on the card, and with it on spacers blowing air up and away from the card, none of these made a huge difference maybe 2-3c at most although the one sucking air away from the card blowing upwards had no effect.

PieEater · 27 Jan 2025 at 17:10

pastymuncher said:
That's a beast of a heatsink and knocking 14.1 degrees C off the hotspot looks to have been well worth doing.

The best thing is I can game (Stalkker2) with the hotspot hovering under 80 and the fans running under 2000rpm as opposed to 3000rpm before which was starting to get on my nerves as my PC is on my desk about 3 ft away.

Drumroll · 27 Jan 2025 at 23:06

Only used thermal tape and few tiny heatsinks on a 3090, before water cooling it front and back.
If the backplate gets really hot it may help, otherwise won’t benefit too much.
in my case, before doing on the 3090, I optimised the heat transfer to the backplate before anything: better quality thermalpads to transfer more and faster heat to the backplate, then add heatsinks, but not a fair comparison any 6800 with the **** design of adding very hot memory chips behind the card, which in a lot of scenarios would cause the GPU to thermal throttle despite the core and the memory next to it being way cooler than required.