AMD's Webcast Phenom II "Deneb"

[AlexWade]

The more I read about Phenom II, the more I like. I've already decided against the Core i7 due to lack of funds. I was just waiting for the official release of Denab before I went with the Core 2 Quad or Phenom II. Of course, I want to see a benchmark on Anandtech before I decide.

 

[Idontcare]

Originally posted by: DrMrLordX

Originally posted by: AdamK47
Anyone know how to make a 24/7 LN2 cooling setup?

This might seem like a throw-away comment but I've given more thought to this question than a sane, rational individual should.

The simple answer is: yes. If you think about it, LN2 cooling is nothing more than phase change cooling, even when it's just a guy pouring some of it into a copper pot + insulation + anti-condensation grease mounted on a CPU. LN2 is going to be at its boiling point when exposed to room-temperature conditions, so most (if not all) of the heat it absorbs will go towards change-of-phase from LN2 to gaseous N2, with the gas itself absorbing very little heat post-change-of-phase due to its comparatively lower density and its tendency to drift away from the contact surface.

So, it's phase change cooling.

A couple years ago I seriously looked into purchasing an on-site LN2 compressor turnkey system.

For the volume of LN2 that would be needed to dissipate ~300W/hr 24x7 I needed a system that cost ~$15k installation and used ~6kW-hr to power. Dimensions were on the order of 1m x 1m x 2m and weighed some 2 tons.

I elected to purchase the vapochill lightspeed for ~$800 after that particular feasibility study

But the author asked about "making" such a system, which basically requires a 5 stage cascade system when working on such a small scale. Despite the setup/install costs though, when most people realize their LN2 dreams are going to cost them ~$1/hr to operate their computer in electrical costs they suddenly get cold feet.

There are (were) many discussions on XS vaporphase forums about the technical challenges of cascade staged LN2 loops. Needless to say no one built one to date and those are the same guys who do build the -140C 4-stage cascades for hobbies.

 

[DrMrLordX]

Makes sense. It would probably be more economically feasible to buy LN2 in bulk from an industrial supplier, not that such a solution would be overly sane. Might be fun though.

I am a little surprised nobody's built a 5-stage cascade system yet. There must be limits to the insanity available on XS and elsewhere.

 

[Idontcare]

Originally posted by: DrMrLordX
I am a little surprised nobody's built a 5-stage cascade system yet. There must be limits to the insanity available on XS and elsewhere.

There are practical limits as to how much power you can pull from the wall before you start getting into needing to wire-up specifically for your cascade system.

The LN2 on-site liquification system required that it be hardwired straight to the breaker box. Not a problem really, just need to hire an electrician, but this is a threshold that most people do not want to cross when it comes to a hobby.

NoL's 4-stage cascade (the one he built for sdumper) basically maxed out a dedicated 110V line. To go any colder (add another stage) he'd need another 300W and that would require tapping a second 110V line.

You could build a 5-stage and get even colder while living within the realm of practical electrical budgets but you would have to give up on trying to get something dissipating 300W+ that cold, a dual-core with half the TDP might work.

 

[DrMrLordX]

That is some serious wattage, but it is to be expected. Honestly I'd love to see equipment like that running off a dedicated wind/solar power system like the ones they pimp on Angel's Nest and elsewhere. They used to brag about running an entire house plus hydrogen electrolyzers on strictly wind/solar so it is not beyond the realm of imagination that systems of that nature could be dedicated to powering an on-site compressor or a quintuple-stage cascade cooler. Again, there is the issue of cost, but it would be an interesting way to overcome practical limits, and it might help mitigate the cost/day of powering such a system in the long run.

If I were the madman spending cash on a 24/7 LN2 cooling system, I'd want something like a 100-litre dewar dripping LN2 onto the cpu, video cards, and board components that needed cooling. While there is ample madness available, the cash is not there. You could probably just position some hoses and nozzles in the right spots and have a computer-controlled drip system set up to regulate flow, maybe by utilizing some load-monitoring software or something along those lines. Actually what I'd really like to see is a case integrated into a huge dewar that could keep the entire motherboard + expansion cards immersed in LN2 but wiring something like that up without letting LN2 leak all over the place would be a pain.

In either case, you'd have to refill your huge tank of LN2 every so often, but at least you'd know you'd have enough on-hand to run the computer for 24 hours straight or longer.