General GPU thermal pad size (width & height)

Me and a buddy are going to do a repaste with Kryonaut, and planning to swap the thermal pads out with Fujipoly at the same time. From the bits of the pads that are exposed it appears that I need 1mm thickness for mine. He has an ASUS SCAR II, which is going to be just paste all over everything so I assume .5mm will be best for that.

But now onto the part I have no idea about, and can find no info on, is what actual size of pads to get. I know it varies from model to model, but I'm assuming something like a 50x60 isn't going to cut it. What would be a good ballpark estimation on the size required?

 

I've never taken the time to look at the length by width - I generally eyeball this and cut from a bigger 100x100+ sized pad. You are correct that a 50x60 won't be enough though.

You're bigger issue is estimating the height/thickness needed - unless you can measure yourself or find accurate specs somewhere anyways. I've found that a very compressible ("squishy") pad around 1.5mm thick is good when you don't know the exact width you need. The Fujipoly are very firm pads and don't have much give. Example: If you use a 2.0mm Fujipoly and find that you only needed 1.0mm you could cause the heatsink to fit poorly and have worse performance than before.

Edit: Not trying to steer you from using the Fujipoly, they are the best pads I've used. Just make sure you do your homework first with the width.

 

I'm pretty sure I need 1mm. Opened the laptop up and was able to cut away a piece of one of the pads that was hanging out and looks like 1mm (thinner than a penny which is 1.5mm). Ended up ordering the 80x40x1mm 12 W/mk Gelid pad. Haven't seen any comparisons with this but looks like it gets good reviews from people that have used it.

 

So what's a good way to find out what thickness pads are needed in case the laptop came with some thick paste instead of pads on the vrms?

I repasted the CPU?GPU but left the original thicker paste around the rest since it seemed fresh enough, but I would like to replace with better pads.

 

I'm guessing you have an ASUS lol.

Put the heatsink on without any paste and see how much space (if you can tell) is between the heatsink and vram. If there's any visible space I'd go with a .5mm. Can't imagine they would use paste with a gap bigger than that. I did see a thread on another site where a guy used .5mm as well when he did a LM application on a 1070 SCAR II.

Another option is to go to an auto parts store and get a piece of plastigauge. Usually for checking clearances in engine bearings and such. Been a few years since I've used it, and never thought about using it for this till now, so I'm not sure if it's soft enough. If it is though, it'd would work quite well.

 

Yep, it's an asus

 

Looks like they use thermal paste instead of pads. You can continue doing that, there's actually a paste which is made to replace thermal pads - K5 Pro. Good thing about this method is that it will improve the physical contact between heatsink and CPU since this paste is more compressible than pads.

 

I wouldn't trust that necessarily.
Asus did the same in GL702ZC and my unit ended up breaking down twice with an identical issue due to fried circuits on the motherboard (which could have started at the VRM's).

 

That may be a possibility but I don't see any reason why a carefully applied paste like K5 would cause such issues, it's non-conductive and its thermal conductivity is no worse than average thermal pad.

 

Actually, the K5-PRO has thermal conductivity K>5,3 W/m.K
That's quite low for a unit such as GL702ZC that has desktop grade hardware.

If you ask me, anything below 8-10w/m.K is quite low for motherboard chips.
Smaller nodes can lead to more heat producing circuitry (especially with currently used inefficient materials), therefore, I don't particularly trust use of a thermal paste in a laptop.
Units like GL702ZC and Helios 500 with Ryzen/Vega need proper thermal pads on the VRM's and other chips that have high thermal conductivity (in fact, I suspect my Acer Helios 500 does have high quality thermal pads on the chips)