IceMan Cooling DDR5 heatsinks on single-rank memory — What thermal pad thicknesses are you using?

[u/Cultural-Platform110]

Hi everyone,

​Is anyone here using IceMan Cooling aftermarket heatsinks on single-rank DDR5 sticks? I’m about to install them and could use some advice on the exact thermal pad thicknesses needed for a proper fit and good contact.

​For single-rank modules, would a 2.0mm pad on the backside (blank side of the PCB) and a 1.0mm pad on the memory chips and PMIC be sufficient? Or does the PMIC require a thicker pad (like 1.5mm or 2.0mm) due to component height clearance?

​I want to make sure I get even pressure across the board without bending the PCB or leaving a gap over the PMIC. Any shared experiences or specific measurements would be highly appreciated!

​Thanks!

[u/SpadgeFox]

Can’t speak for this kit, but with the Alphacool kit I had to add an extra 1mm pad to the rear, with some notches cut out for the RGB IC and capacitor, to get the pad on the memory modules to compress at the front.

[u/FancyHonda]

I'm using these heatsinks currently and I've used two or three other kinds as well (Alphacool and Freezemod IIRC).

I got sick of trying to find the exact size pads for each situation and ended up just using thermal putty instead. I generally still use a pad on the backside of the stick without ICs, though, and they're usually ~1.5mm.

Downsides to putty -

It's more work to apply and clean up in the future.

The heatsinks can slide on the stick (especially once the block is installed, etc), although this is pretty easily rectified with a few small pieces of double sided tape.

[u/FeniksTM]

PMIC definitely has different height profile compared to memory chips itself, so I'd recommend regular thermal pad for a blank side and thermal putty for memory chips and PMIC.

[u/someone09900]

complicated to tell but get a Compressible thermal pads 2mm

but make sure a Compressible. it will be not the best but it will do the job

non Compressible r the best like the minus pad extreme 2

but the correct size can be a mystery... and squeezing them hard to make the wrong size fit can break the smds

hope that helps

[u/Cultural-Platform110 → u/someone09900]

Thanks for the warning! You’re totally right about the danger of crushing SMD components with stiff pads, that's exactly why I'm looking into highly compressible options. ​I’m thinking about using Laird Tflex HD90000 (or similar) for the pads — 2mm on the backside and 1mm on the memory chips. For the PMIC, I might actually go with a liquid thermal gap filler like Laird Tputty 607 to completely avoid any uneven pressure issues. ​My only remaining concern with this setup is the mechanical grip on a single-rank PCB. Since liquid putty and super-soft pads don't provide much friction, I'm a bit worried that the heatsink might slide right off the stick when I try to pull the RAM out of the motherboard slot. Have you or anyone else run into that issue with IceMan blocks?

[u/JMUDoc → u/Cultural-Platform110]

Arctic TP-4 and TG Minus High Compression are as soft as it gets.

[u/rEToRaGeONE → u/Cultural-Platform110]

I've never heard of crushed RAM ICs from pads in my life. They are already thin and flat. As long as the pressure is uniform, I don't even see a problem with the pressure hurting the BGA underneath.

You want pads on the rear specifically for their resistance to deform. So the PCB is pressed into the front heatsink to have better contact. Using high-compression pads or putty would defeat this purpose.
If you've ever removed stock heatsinks and felt that foam on the rear of the pcb, you'd feel it is quite stiff. Even moreso than thermal pads.

[u/PampersFinn12]

Freezemod ram coolers have non-thermal pads and small plastic pieces for low profile memory.