Thinkpads Forum

Perhaps this is obvious, but it's not obvious to me.

Some members advocate bending the Auxiliary pads of the HSF to meet the GPU and/or Northbridge chip surfaces, and then using thermal compound to make the contact instead of using elastomer heat conducting pads. The gap must be less than a mm for this to work, and if there's any relief between the HSF and the bracket holding it, I'd expect air to be introduced from any significant movement (like carrying it in a bag).

I'd like to hear how to do this. When the motherboard is assembled in the case, I can't see between the pads and the chips.

What techniques do you use to guarantee these tolerances on four corners of two separate surfaces at the same time?

Do you remove the motherboard from the frame, then adjust the HSF while it's possible (mabye) to sight from the edge and see any light to show the gaps? And then trust that it will fit the same when assembled?

Do you 'tap' the pads to try to note from the feel that there's a gap?

I haven't read any reference to using feeler guages.

So how do you do this?

Thanks,
Bret

I think the main thing that needs to be done when removing the pads is the retaining clip(s) that apply pressure down on the HSF over the chipset and GPU (if present) needs to be tightened up. Use pliers to bend the spring section that makes contact to the HSF.

Actually bending the HSF is optional. As you'll notice, it is flexible so as long as you apply pressure down onto it it will make contact.

Now, the complication here is how to achieve coplanarity between Chipset / GPU dies and the HSF plate. But think about how shallow the angle is going to be - one edge of each die will certainly be in contact with the HSF plate, and the other edge will be much much much closer than it was with the pad in place. There will be no air gap, just a very tiny "wedge" of thermal paste. Much better than the old pads.

And of course, if you have a discrete GPU you have two components which differ slightly in height, so if you were to try and achieve full coplanarity with both, you would need to bend the flat plate ever so slightly in two places. I say leave it and just tighten up the retainer springs. Has worked great for me.