Overclocking with Liquid Nitrogen
The difference between conventional and extreme overclocking is largely a matter of temperatures. In theory, the distinction is subtle. But in practice, the latter involves major considerations (like condensation, for example). You have to take special care to protect your hardware from the ice (and related water droplets) that forms on the cooler.
There are multiple ways to prepare sensitive electronics for the rigors of extreme overclocking. Similar to the fashion industry, those styles evolve and come back in vogue years later. Without going into too many details, the most popular techniques are:
- Vaseline: Coat the surface to keep water from coming into contact with the PCB. It's quick and cheap, but hard to clean up. In addition, certain chips can be very sensitive and malfunction in its presence.
- Plasti Dip: This is a plastic that can either be applied with a brush or an aerosol can. Once the solvents have evaporated, the layer solidifies. It's more expensive (about $10 per can), but its inconveniences are the long application time and difficult clean-up.
- Kneaded eraser: This is a sort of modeling putty. It's also quite expensive at around $10 per motherboard. On the flip side, you can re-use the material, and it's easy to clean up (depending on how long it was in contact with your hardware).
- Neoprene: This is simply covering the motherboard with a layer of synthetic rubber. Clean-up can't get any easier than this, but the preparation time is quite long. This technique exposes more of the motherboard because there is not a tight seal. Water can therefore infiltrate.
Having lost USB ports on multiple motherboards last year, I decided to skip Vaseline this time around. My motherboard is covered in paper towels cut to size, which serve as the final protection in case water gets under the first line of defense.
Extreme overclockers aren't interested in aesthetics. Though it's far from beautiful, this piece of neoprene is trimmed to hug the motherboard's PCA as tightly as possible. Cutouts accommodate the processor interface, inductors, capacitors, and PCIe slots. Once finished, it will be coated in adhesive for support and partial waterproofing.
The back side of the motherboard is less vulnerable, but still important to protect. We use a combination of kneaded eraser and an anti-static bag. Just the putty would be sufficient, but covering the entire motherboard with it takes a long time and costs quite a bit. Therefore, we created a barrier of kneaded eraser around the border of the motherboard and covered all openings, then sealed everything water-tight with the anti-static bag. Anti-static? Only because it was sitting around when we were searching for a solution!
After many hours spent in the motherboard's BIOS, we came to a realization that only become funny later: our first three sessions failed and were a complete loss due to a small and trivial voltage setting. Without it, we couldn't get the multiplier above 60x.
The problem wasn't related to stability. A combination of 102 MHz x 59 yields a frequency above 6 GHz, and that was completely stable. But the system would hang without fail if we switched to 100 MHz x 60. After tens of liters of liquid nitrogen, a bottle of gas, and more than 10 hours of chilling to test the BIOS, processor, RAM, and operating system, we finally stumbled on a solution: the “PLL SFR” setting must also be increased to more than 1.1V instead of 0.9V to unlock the higher multiplier.
After hurdling this roadblock, we were able to push our -7700K a little harder.
We reached about 6.6 GHz on Cinebench R11.5. World records won't be broken with this sample, but for a first attempt with a -7700K that wasn't hand-selected, it is quite satisfying.
We achieved a little more than 6.6 GHz under Wprime 32M and 1024M.
In the end, we logged about a dozen results, and they're all available on HWBOT. Without question, these will be vastly improved in the weeks to come. This was just a first attempt.
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