High GPU Memory Junction Temps (98C-104C) on GDDR6X – Thermal Pad Replacement Guide
Noticed my RTX 3080 / 4080 memory junction temperatures were creeping up to 102C during 4K Ray Tracing, causing the card to aggressively downclock core clocks by 150MHz. Here is the teardown analysis and exact pad thickness measurements if anyone else is experiencing this:
Root Cause:
Factory oily silicone pads deteriorate and compress unevenly after 18-24 months of heat cycling, losing direct dielectric contact with the nickel-plated copper coldplate.
Replacement Pad Specs:
- Front VRAM: Gelid GP-Ultimate 1.5mm (15 W/mK)
- VRM Mosfets: Gelid GP-Extreme 1.0mm (12 W/mK)
- Backplate contact: Gelid 2.0mm or Upsiren U6 Pro thermal putty
- Core paste: PTM7950 phase change pad (40x40mm cut)
Results:
Memory Junction dropped from 102C -> 74C under full FurMark load, and GPU Core dropped 6C. Fan RPM dropped from 2,300 RPM -> 1,450 RPM.
Responses 2
Can confirm PTM7950 is pure magic on direct-die GPUs. Solves the pump-out issue permanently compared to normal paste. Great writeup!
For anyone doing this on Gigabyte cards specifically: always measure your stock pads with digital calipers before buying! Some revision 1.1 boards use 1.0mm on VRAM instead of 1.5mm.
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