So Speaking for 3080 ftw3 which Evga cheaped out on pads. There is a guy which used 3mm gelid extreme and saw up to 7C drops
 
Is back side of PCB is 2mm or 2.5mm
 
""For other parts of the card i needed 2.5mm to make it to the PCB. (i put pads on the back side of the VRMs)""
 
this indicated its 2.5mm. 

Dang... all I can get today is 6W/mk stuff... but I do have the optimus block and back plate coming... so debating on trying with the pads I got or just waiting another 2-3 weeks or more

Pads are good if you don’t want a mess, but less is more for thermals.

Hey I have a question.
 
I just want to remove backplate and apply some pads. The screws holding backplate also holds the main cooler /heatsink. Lets say i put the card face down and gently removed backplate, do cooler jiggle or come off ? I dont want to screw up original puddy and pads on VRAM and VRM

You do not need to remove the cooler screws. There is one hidden under a sticker, and 3 with a nut on them. 1 of those 3 is a pain to get the nut started on though. I used some precision tweezers to hold that nut in place, while spinning the screw. Also, my sloppy measurement showed 2mm thick ram pads on the rear, but I could have been off.

Best bet is 2.5mm with good squeeze force. Thanks for your input. This mod is much NEEDED for VRM area cooling.
 
IF you seek top core overclock.

Back of the PCB is 3mm needed. I used 3mm Gelid Extreme

I just don’t think you’ll get good compression with 2.5... for the VRM areas

zurvv
Some pad updates.
Note, i used fuji ultra extreme - which doesn't compress much. So it isn't useful to compare the below info to other more squishy pads (like the ones that came with the card)
 
I replaced the putty and use a .5mm pad. It made contact. (i also put a layer of TIM too.)
For the ram i used a 2mm pad (1.5mm plus a .5mm - there wasn't a fuji  extreme 2mm option)
 
First, ram and the rest of the card pretty well cooled. I never saw the ram hit more than 70C. (with 30min load of timespy extreme with +750.) That is read from the ICX3 sensors. 
The problem is the GPU, it is hotter than it was before (and thus didn't OC was well.) I'm not sure which of the pads is causing the problem (my guess would be the ram)
 
*sigh* those fuji's cost a ton. I'll most likekly have to replace it was a 2mm pad that has more give. I have some TG pads around.
 
I also put TG pads on the back of the card on the ram. 2mm is right.
For other parts of the card i needed 2.5mm to make it to the PCB. (i put pads on the back side of the VRMs)
 
(for TIM on the GPU i used TG Kryonaut Extreme)
 
 
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UPDATED:
I replaced the fuji ultra extreme with TG pads (which compress better.)
My size suggestions for replacing pads with using TG
 
2mm for ram, .5mm for putty replacement, 2mm for ram on the back. 2.5mm for PCB to back.

i am about to do 2 new builds.. one is with the xc3 ultra with the EK waterblock, the other is with my KP.  Do you suggest fuji pads??  i oknow i need a bunch, some came with the waterblock but id rather use really good one

confused for the backside vram
we should use 2mm like jacobf written or  3mm like seandude05 written
 

 

Just saying, the PCBs are similar, backplates are similar, and on my 3080 FTW3, I had to use 3mm pads to properly fill the gap.

To clarify, on the memory, you probably need to use 2.5, but the rest of the surface area needs 3mm.