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Has this product even been made available yet? They were targeting a "late july" release... would like to buy it...

Interesting, didn't realize the delta T across components was so small, even with less than 1 degree the theory behind a FPSC will still work. You'll be decreasing the inlet temperature into the cpu by a tiny amount which will then increase heat transfer rate. Probably not significant tbh, but would be an interesting experiment.

The CPU and radiator are both elements of a watercooling loop which create ΔT. The radiator decreases and the cpu cooler increases water temperature. This must be the case in order to transfer heat. The FPSC in this case is a third ΔT creating element, one which also decreases temp. I understand that it isn't a new loop idea or anything and stated as such in my original post, saying that it is similar to a chiller loop. As for how efficient it is? Not sure, IIRC efficiency of the stirling cooler increases when hot and cold end temperatures converge. Most studies i've seen are dealing with efficiency at very low cold side temps (~80C or less). There are huge disadvantages to FPSC cooling in computers, but I just wanted to put it out there in case anyone else is looking for a different idea for a project.

Wouldn't there be no heat transfer without delta T across heat source and radiator?

Note the direction of flow arrows. Hot Liquid from heat source first travels to radiator in order to cool to near ambient levels. Then it is run through the cooler which brings it down to sub ambient levels. Placement of the reservoir and pump could just as easily be after the radiator.

Honestly no idea, but way less cooling potential than LN2 and any gas refrigeration type cooling. This could be a daily driver type thing though. In a tier list it would be LN2>Waterchiller>FPSC+Liquid cooling loop>Liquid cooling loop. Another option would be to place the FPSC directly on the CPU die, but this increases risk. More something you add to a liquid cooling loop to drop 5-10C below ambient. I never got far enough to test the effectiveness of the idea.

shoutingsteve is correct. Galliums specific heat is only 0.37 J/g K, water is 4.19 J/g K. Using gallium will result in higher fluid temps for the same volume of liquid as water. In order to produce the same results as water cooling, you would need more volume of gallium, larger radiator and more flow. Ammonia has higher specific heat, but would be much more expensive than just building a larger watercooling setup. If you want to change working fluid you could explore a compressible gas and turn your water cooling loop into a refrigeration loop. Replace cool air with CPU/GPU block. and insulate this block so that only heat is transferred between processor and gas.

You would probably want to insulate your CPU/GPU waterblock so that heat isn't transferred to the oil. If you do this, there is very little chance the oil will cool much. If you want to cool the oil too, mineral oil has a freezing temp of -4C. This can be lowered further by circulation. A small pump moving the oil around would probably be enough to prevent any freezing and would act as extra cooling for your MOBO.

A couple years ago my team and I were working on a proposal for our final year engineering project. We were heavily considering a novel (we think/thought) method of sub ambient water cooling, similar to using a chiller. Instead of a water chiller or TEC (garbage efficiency), we were considering a free piston stirling cooler (FPSC from now on). Most engineers are familiar with the stirling cycle, usually input of heat (fuel being burnt for instance) and outputting mechanical work (torque @ RPM). However, if you invert the cycle and INPUT work, then this creates a temperature differential which will "pump" heat. This is what is known as a Stirling cooler. What is free piston? Instead of a rotating crank and flywheel, a solenoid is used to actuate the cycle. Working fluid is helium or similar gas IIRC (completely sealed). This has a benefit of making the FPSC compact, very low maintenance and quiet. Efficiency depends heavily on the hot side and cold side temperatures, but is much better than TECs. I've heard of FPSC's used to cool: IR cameras and quantum computers. Cold side temperature can be as low as -150C, although its efficiency decreases with temperature decrease (efficiency 0 at minimum cold side temp). Where do you get a FPSC? This is the most difficult part. The most easily available was used in a small electric cooler sold on the commercial market, as well as for medical transport (search "Twinbird FPSC Portable Freezer"). When we were doing the research for this project we bought the 2004 coleman cooler for 400 CAD. Unfortunately I did not keep it and left it with my school. Whats cool about this cooler is it could be implemented in a cooling loop, see below. It will need a water block like device to transfer the heat from its cold end to water. We didn't end up doing much with the cooler, due to us thinking it was underpowered for PC cooling (draws 12V 4A). But maybe someone here is willing to give it a go and find out if there is a way to get more performance out of it. Note: PV is proportioning valve for bypassing FPSC, not necessarily required.