Here are the results for the direct die mounting
, without IHS
:Water inlet temperature: 23.65C
Core package average: 69.6C
Delta core/water: 49.05C
Flow rate: 1.17 Gallon/min
This is how I applied TIM:In summary direct die mount does reach about 5C lower core temp than with IHS on! During benching the temperature improvement is very noticeable
This is with direct mounting of KOC WXE over the die, without removing CPU retention, two nylon washers are added in the retention to ensure CPU mounting pressure. The waterblock then can be mounted with "figure 8" tightening method. I have repeated it twice and got consistent results.
I have also tried to add a thin silicon rubber pad which is slightly (very slightly, may be 5-10 thousands of an inch) thicker than the die. I thought it could help protect the die and balance the mounting. But the performance with this method is poorer than with IHS on by about 1C core temp. The reason I think is the additional forces required to compress the rubber, it offsets the mounting pressure and affects contact between silicon die and waterblock. So unless you are sure about the mounting pressure, adding rubber pad is not recommended.
If you decide to do direct die mounting, you are aware of the risks as I have sacrificed a processor. Be sure to use "Figure 8" method to tighten the screws and constantly check the compressing of springs are even. It is also good practice to tape the surface of the PCB to prevent scratching. Don't tape the surface mount caps!
Because they are only a little shorter than the die, with tape it will be higher than the die.Rule of thumb for mounting direct die:
1. Try to mount the heatsink as flat as possible and always use "figure 8" method to tighten screws/springs and only tighten quarter/half turn each time.
2. Never fully compress the springs. The mounting force will increase enormously after springs are fully compressed.
3. Too little pressure is also bad, which may cause poor pin contact in the socket. Normally I tighten the springs to 2/3 or 3/4 of the amount of full compression.
4. Use electrical tape to protect the CPU PCB surface from short circuiting. But never build tape higher than the die (for example don't put tape over the surface mount caps on Haswell cpu).
5. Center your heatsink/waterblock with respect to the die/mounting holes. Off-center mounting will cause tilting of the heatsink.
Even with this procedure I think this is still chance of damage since we are human. Think about the risk and gain before you try.Edited by foxrena - 7/6/13 at 2:14pm