[SOLVED] Which cooler is better for Direct die cooling?

[ckooii]

Hello friends!

i7 7700k delidded and without IHS. Need to cool it somehow. The only thing i have is a Deepcool Assasin ll .

People say such huge coolers are too big for direct die cooling, cus the crystal is so small, and a big cooler base and a tall tower with long pipes is ineffective in this case.

Could someone please explain the physics, is it actually true and do i need a low profile cooler like the Noctua NH-L9x65? I guess im not that good in physics after all, so need help.

Thank you!

 

[CompuTronix]

ckooii,

What "people say" is incorrect for the reason given. Air or liquid coolers will function normally on a delidded processor, with or without the IHS.

With respect to direct Die cooling, thermal dissipation, whether by means of air or liquid cooling, is affected by the number of thermal gradients, type of material, thickness and surface contact areas of each.

Heat originates at the microscopic nanometer scale transistor junctions deep within the Cores, then dissipates over relatively large areas and thermal gradients to the cooler, which is a considerable distance from the Cores at about 3 millimeters (about 0.1 inch); 3 millimeters = 3,000,000 nanometers.

Although some heat dissipates to the substrate, socket and motherboard, most heat dissipates to the cooler through several thermal gradients; Cores > Die > internal TIM (Thermal Interface Material; either solder or paste) > IHS > external TIM (paste) > cooler.

Direct Die cooling removes two of these gradients. Intel's internal pTIM (paste Thermal Interface Material) imposes the greatest loss of thermal efficiency, whereas the IHS accounts for only a few degrees.

However, there are other factors involved when considering direct Die cooling.

Previous Generations of Intel processors used a more rigid substrate that is 1.1mm thick, while 6th through 8th Generation is only 0.8mm thick, which means it's relatively fragile.

Since the substrate is supported by the socket perimeter, when weight and pressure from the cooler is applied to the Die (especially a large heavy air cooler), without an IHS to support the mechanical load, the substrate will significantly flex in the area around the Die. This forces the socket pins to deflect, which causes a loss of contact with the substrate pads that in turn creates connectivity failures such as PCH, RAM and PCIE slots. Also, when the substrate flexes it can crack the Die.

Moreover, the Die can be cracked by impatiently mounting the cooler, when special care and attention is not given to very gradually and evenly tightening the fasteners in an "X" pattern. Further, the absence of the CPU retention bracket and the IHS alters the design dimensions for the cooler fastening hardware, which in turn alters the contact pressure. Solving these mechanical challenges requires that you implement a "creative" home-made solution ...

OR ...

To properly implement direct Die cooling, it is instead highly recommended that you order a compatible socket 1151 Delid Die Guard that compensates for these mechanical differences, and to ensure that you don't crack the Die. However, since the thermal difference between direct Die and remounting the IHS is only ~3°C, there's little to be gained compared to ~20°C by just replacing Intel's paste.

Whether you delid and use direct Die or remount the IHS, delidding requires that you use only liquid metal TIM. Paste (pTIM) will fail in a relatively brief period of time. Due to thermal cycling, a process known as “pump-out” will expel pTIM from between the Die and the heat sink surface (IHS or cooler), whereas liquid metal is very resistant to pump-out.

Although Intel's pTIM is formulated to resist pump-out, it still degrades over time, losing its thermal bond with the Die. The most recommended liquid metal TIM is Thermal Grizzly Conductonaut.

CT

 

[ckooii]

that is exactly what i needed and much more, thank you sir.