Beginning Liquid Nitrogen Overclocking

Computer CPUs are typically "air-cooled", meaning that after the heat has conducted to the heatsink, it is extracted by blowing cool air across the fins. While it’s cheap, quiet and effectively does the job, it’s impossible to cool the CPU down below the ambient air temperature. In liquid nitrogen (LN2) cooling, LN2 (boils at nearly -200°C) is poured onto the a specialised heatsink to extract heat rather than blowing air.

I’ve had the opportunity to try this out first hand at the Gigabyte OC Workshop this Monday, with the TeamAU crew (dinos22, deanzo, and uncle fester). LN2 overclocking on the Z68X-UD4, Core i5 2500K, GTX470 and the GTX580 SOC.

How does it work?

The reason why LN2 cooling works so well is not just because we’re pouring really cold liquids onto the heat source; it’s also because a lot of the heat energy is absorbed by the process of evaporation. To make sure that the LN2 doesn’t just boil away and splatter away, there are custom designed CPU "pots" that are essentially a heatsink base with a cup to hold the LN2 while it evaporates.

I’ve been told that the colder the CPU gets, the faster it can run. (That, and to save the CPU from blowing up from pumping an insane core voltage into it.)

Why is sub-zero overclocking more difficult?

The biggest difference between the conventional air cooling and even cooling below room temperature is that condensation builds up as moist air settles on the cool surfaces on the equipment. As we all know, water and electronics don’t mix. That’s why we see so many fans, hairdryers and mounds of paper towels in LN2 setups.

Given that the CPU can only be overclocked so much below a certain temperature threshold, on the one hand we need to keep the CPU below a certain temperature, while on the other hand we can’t drop the temperature too much otherwise we’d get what’s called a "cold bug" and the computer would freeze – as in, lock up and stop working.

Usually when the computer locks up, it’s easy enough to hit the reset button to reboot and try again, but with subzero cooling there’s also the "coldboot bug" where there computer will not start unless it’s warmed up above a certain temperature. I suspect the coldboot bug is due to arithmetic underflow on the temperature sensor that falsely triggers the thermal protection circuit. The quickest way to fix this is apparently putting a butane torch to the LN2 pot…

Because temperature and voltage regulation is so critical, external temperature probes are used to get to most accurate readings from as close to the chip as possible. We can’t rely on the built-in sensors because they’re not designed to operate at extreme subzero temperatures, and many motherboards are simply incapable of reporting temperatures at that range.

What are the risks?

As mentioned before, the biggest risk in going sub-zero is the build-up of condensation wherever that’s colder than ambient. There’s a good amount of preparation work to be done before anything is plugged in, including insulating exposed circuitry on the motherboard against moisture and the cold, as well as making sure that the cooling device and temperature probes is mounted correctly.

Even when all precautions are taken, things can still go wrong. We were shown a dead $600 GTX580 SOC with a resistor gone kaput.

The Gigabyte OC Workshop

The workshop was an incredibly fun experience, and it’s a rare opportunity to have the professional overclockers share their insights and experiences as well as an excellent tutorial on LN2 overclocking.

It’s a shame we didn’t beat any records on our first try, but I did walk away with a Gigabyte X58A-OC Motherboard having guessed the closest top 3DMark11 score. The runner up (Justin) walked away with a Gigabyte Z68X-UD4-B3 Motherboard.

Final words

A big thanks to PC PowerPlay and Gigabyte for hosting this awesome event. It’s incredibly difficult to even have a go at LN2 overclocking because it’s just a different beast. Reaching out and teaching us how it’s done really saves the stress of not knowing what’s right and would definitely save a bunch of dead hardware.

Let’s do this again!

Chinese New Year Twilight Parade 2011

6 February 2011
George Street, Sydney, Australia

Craig Mundie talks NUI and Avatar Kinects with Dean of Engineering and IT at the University of Sydney

On Tuesday, as part of the Dean’s Lecture Series, Microsoft’s Chief Research and Strategy Officer Craig Mundie demonstrates a virtual persona based teleconferencing technology known as Avatar Kinect which was announced at CES 2011 earlier this year.

This public demonstration was the second in Australia after the Melbourne event a day before, and was in attendance of over 300 people in Sydney, a hundred more than the first.

The lecture focused on next generation computer human interaction interaction “Natural User Interfaces” (NUI), set to expand the possibilities of sterile computer control in the operating theatre, remote virtual gaming and a virtual receptionist. Natural user interfaces is set to remove the learning curve from today’s user interfaces, taking advantage of metaphors from the physical world.

Craig explains that while the step from telephone was to television, the next step is telepresence. I think that the use of an avatar is a great step forward, especially since many of today’s users are already comfortable with taking upon an online persona through many of the video games available today.

Microsoft Research have been rather active in NUI development, and many of its work could be found found explained in quite simple terms at MSDN ‘s Channel9 since TechFest 2010.

Awesome visits to IT companies this week!

We have had a great time this week, and thank you to everyone whom attended. This Macquarie sign is from the top of their new “activity-based” building at Shelley St. For those who missed out, it’s not like any other office buildings you’ve ever seen before. Keep an eye out for when SUITS runs another one of these extraordinary visits again perhaps next year!

I want to take this opportunity to thank Will from Google, Robyn from Atlassian and Larissa from our sponsor Optiver whom have worked with me throughout the time leading up. A special thanks goes to Anna from Macquarie because she has made our visit possible even at such short notice! They have put in so much effect to make this all possible, and it’s easy for this effort to go unnoticed.

I promised to make the photos available, and here it is after the break. I’ve only included low-res photos here, but feel free to click through to get to the full quality photos. The links and resources are also after the break.

Feedback. I’d love to know what you thought about this event. Send me an email with any thoughts or comments, in particular:

1. What did you get out of the day?
2. Which parts did you like best (and/or didn’t like), and why?
3. How can we make this event even better for next time?

Read more »

My TechEd Australia 2009 photos are now online

I know it’s a while after TechEd finished, but they’re now available on my Flickr!