Dry Ice [Warning 56k]

[CanadaRox]

Originally Posted by Eldonko

- DI is max -77C, not -90C ;)
- You may want to invest in a digital thermometer and mount probe on bottom of pot (see pic).
- Dice will cool best if you crush first, and maintain a few inches, packing down often.
- Use about 2 oz of methanol or whatever, as long as its 90%+

I read somewhere that certain liquids would lower the sublimination point of DI, similar to how salt and ice water will be colder than just ice. Google manages to turn up this though:
Ethanol/Dry ice -72
Acetone/Dry ice -78
Isopropanol/Dry ice -78
Sulfur dioxide/Dry ice -82
Diethyl ether/Dry ice -100
So clearly (and unsurprisingly) the -92°C was wrong, but with Diethyl ether, DI can get down to -100°C. Too bad it is extremely flammable.

And thanks for the advice on how to fill the tube. We were using small pellets about 3-5cm by 1.5cm by 1.5cm, and we used WAY too much ethanol (to the point where it was almost overflowing when we added more DI).

[Eldonko]

All liquids that wont kill you + dice = -77C (0 heat load). If you have a digi thermo you will see that the base of the pot is closer to -65C depending on vcore. You can pick one up on ebay probably for pretty cheap, $50-60, new they are $200+. For thermal paste I generally use a mixture of AS5 and AS Ceramique, the ceramique prevents the paste from freezing and keeps it effective.

Just a couple tips, if you have any questions just ask. :)

[Babrbarossa]

Do people ever freeze both sides of the board when overclocking quad cores?

[Eldonko]

Nah, the best bet for high heat cpus is to have a 3 inch solid copper pot with high mass. Not cheap though, the copper alone is close to $300.

[Babrbarossa]

Do you know of anyone who has ever tested a two piece pot against a one piece? Two piece meaning a pipe fused to a base, of course. it would be so much cheaper to make one this way..

[Eldonko]

Yeah a few people tested this, I had a big thread about it at ocx before the server crashed and all data was lost. Unfortunately its gone now.

The difference is the delta between idle and load. A solid pot with decent design and mass can hold a delta of 2-3C, a brazed pot is more like 5C+ delta. Not that big of a difference for someone just wanting to have some fun but if you need that 20 extra Mhz to crack a WR then the solid is essential.

A new trend in pot design today is the "bullet". This is a two piece pot with the bottom copper threaded into an aluminum top. Saves alot of $ in copper and is in between brased and solid design in terms of performance. Example these guys made by duniek



Thread

Anyway, sorry for going OT in your thread CanadaRox

[3.0charlie]

You are aware that copper used in conjuction with aluminium will generate in time a galvanic corrosion of the aluminium at the point of contact.

[Eldonko]

I guess, I dunno tbh, I dont have a bullet pot myself. I think if you just put together when benching you will be good but these are a new idea so who knows what happens over time.

[3.0charlie]

Al and Cu can be used together as long as the mating surfaces are not in direct contact - apply a tape or a corrosion inhibitive compound on the threads, or solder the joints to prevent liquid ingress in the threads (might be tricky to solder the inside though). The use of an o-ring is a start but a seal to close the inner joint is needed too.

Anyway - some info. from my Materials Course back in my Uni. days.

[CanadaRox]

Just got back from work, and I've got a nice new PC Power & Cooling 750W Silencer on the table. Good thing my dad can drive by Canada Computers on his way home from work. Got some pictures of the PSU of course.

Box:
Image of Box - Photobucket - Video and Image Hosting

Specs:
Image of Specs - Photobucket - Video and Image Hosting

Big mess of cables:
Image of Huge mess of cables - Photobucket - Video and Image Hosting

Cables include:
24-pin, 2 x PCI-E 8-pin, 2 x PCI-E 6-pin, CPI 8-pin, CPU 4-pin, 6 x SATA, 8 x molex, Floppy (which I can connect to my motherboard to provide extra power to the PCI-Ex16 port)