The Main Event: Overclocking With LN2
With all of that practical information out of the way, it's time to set aside our water-cooling loop and set up for liquid nitrogen.
Conductonaut versus Kryonaut
At ambient temperatures, Conductonaut performs better than classic thermal compounds. But experience tells us that it doesn't fare well under the influence of extreme cold. With this in mind, we maintained 2.1V Vccin, 1.4V Vcore, and 4800 MHz core clock rate settings.
- With the cooling pot's base at 20°C, Core Temp indicated a power consumption of 330W and core temperatures ranging from 80 to 98°C.
- At 0°C, power consumption reportedly dropped to 303W. That was naturally a surprising result, so we confirmed it with the monitoring capability of our Cooler Master MasterWatt Maker 1200. Lowering the cooling pot's temperature by 20°C also dropped the core temperatures by as much as 30°C.
- At -20°C, power consumption fell as low as 285W. The cores cooled off by another 25°C.
- At -40°C, our power consumption measurement was 275W (or 55W less than our starting point). The hottest core measured 17°C, while the coolest was at 1°C.
- At -60°C, the system became unstable after we observed rapid and significant core temperature increases. This is our sign that the thermal paste stopped doing its job.
This test confirmed that Conductonaut, a high-performance paste at ambient temperatures, doesn't work below -60°C. Our experiment also gave us several interesting data points to show the direct correlation between CPU's operating temperature and power consumption. Although it's less effective than Conductonaut at ambient temperatures, Kryonaut is a better choice for extreme overclocking.
Direct Die Frame versus IHS
Next, we set out to see if the benefits of direct-die cooling mapped over to overclocking with liquid nitrogen.
Although we did our best to record accurate and precise results, bear in mind that it's very difficult to achieve repeatability with LN2.
With the cooling pot at -50°C, our DDF performs a lot like the Core i9 with its IHS intact. At the next temperature increment, direct-die cooling takes a small lead. But at -70°C, where we thought the gap would widen even further, both approaches converge once again. Tests at -80, -90, and -100°C resulted in similar observations. Whether you use direct-die cooling or a heat spreader between the die and cooling pot, the outcome is near-identical.
The highest stable frequency we reached that'd still run Cinebench R15 was 5800 MHz. Not bad for a CPU that gave us so many problems at launch using more mainstream approaches to cooling.
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