[This is not very scientific, however it is notable. At 7.5W/m-K vs the installed SYY-157 at 15.7 W/m-K it performed better in real world low clamping force situations.]
A great performing, low maintenance, alternative to thermal paste in PCs, GPUs, laptops, servers, consoles, etc. is one of the more recent phase change materials (PCMs). Phase change materials for use in PCs typically have the following properties:
- The PCM is a thin, easy to tear, solid grey rubbery sheet
- The PCM sheet is sandwiched between two clear plastic films
- Solid at temps below 60° C, and a very sticky and thick liquid above
- Fairly easy to tear
- Does not separate from the plastic films easily
In particular the Honeywell PTM7950 has become very popular in the modding and PC building community. See the LTT video here for some more background and information.
In particular phase change materials have these properties:
- Low maintenance as they do not suffer from "pump out" due to thermal cycles
- Excellent surface wetting to "connect" with the target
- Easy application - seriously READ THE GUIDE, it has pictures!
- Working well in low clamping force scenarios
However there is one big downside - availability. Honeywell PTM7950 is not carried by any supplier a normal individual can order from (as of 2/2/2024), forcing either very expensive purchases from small suppliers or taking a big risk on marketplaces like Amazon or Aliexpress.
Laird Tpcm 7000
BUT! Honeywell is not the only company making PCM products for the high-end market. Allow me to introduce Laird (Laird Technologies Inc. a DuPont company) and their equivalent, Tpcm 7000. This is available in a large sheet (9" × 9" × 0.25mm A18172-10) from suppliers such as Digikey, Allied, AVNET, Mouser, and Sager. Digikey shipped me one for $34 (2/2/2024)!
For specification comparison of Laird Tpcm 7000 vs Honeywell PTM7950:
| Property | Tpcm 7000 | PTM7000 | | Thermal conductivity W/m-K | 7.5 | 6.0-8.5 | | Thermal resistance °C-cm^2/W | 0.10-0.06 | 0.04-0.06 | | Volume resistivity Ω-cm | 5.4×10^15 | 2.1×10^14 |
[Now, while there are some differences in these values, for all practical purposes these are the same materials. Measuring thermal conductivity is challenging and the standard used here according to both is ASTM D5470, but Honeywell mentions that they modified D5470 for their thermal resistivity measurement. I have not done a deep dive here, but neither is being shady or difficult. Thermal is HARD, and mapping the D5470 values to a specific application is also difficult.]
My Results
- Clean heatsink and chip with towel of old SYY-157
- Wipe with a clean tissue and alcohol to get clean
- Final wipe with one stroke per clean tissue, in one direction only - no "back and forth"!
- Cut a square of Tpcm 7250 with a scalpel, it was pretty easy
- Peeled the bottom liner film with Laird markings off Tpcm and applied to chip
- Rubbed the top liner side multiple times to get firm attachment
- Leave for 1-2 minutes for Tpcm to stick (as per the instructions)
- Peeled the bottom liner carefully with tweezers, folding it back on itself (seriously, read the instructions)
- Apply heatsink
- ...
- ...
- ...
- Profit!
NVIDIA/Mellanox Connectx-5 Ex Dual 100GBE Ethernet cards
My Workstation:
while ($true) {
Get-Date
Mlx5Cmd.exe -Temperature;
Start-Sleep -Seconds 3;
}
Before application: Workstation Booted "Idle" soaked temperature: 86 - 87°C
After application: Workstation Booted "Heavy" soaked temperature: 84°C
My Homelab Server:
mst start
while true; do
date
mget_temp_ext -d /dev/mst/mt4121_pciconf0
sleep 3
done
Post application: Workstation Booted "Heavy" soaked temperature: 100°C
Zotac Gaming GeForce RTX 3090 Trinity
GPU Temp: 81.3°C
Hot Spot: 102.2°C
After application:
GPU Temp: 81.3°C
Hot Spot: 94.1°C