Temperature problem .....

[dermedt]

Hi Everybody!

We did our first run with dry ice yesterday, but we found ourself against a serius problem.
The CPU idle temperature could not fall under -25 °C .The ice temperature was about -60°C.

The container was made of brass ( not copper) .Can it cause the problem?
Or can can be the rise of the problem that the thick of the support is only 4mm?
We used alcohol too , but we didn't know the quantity .

Can anybody help plz?

Thanks.

[marvt74]

Brass has a pretty poor thermal conductivity which is probably one of the main problems. (Brass - 69.33, Aluminium - 136, Copper - 231)
Also sounds like you may have used too much alcohol i'd expect ice temps in the -70's unless your thermometer was inaccurate.

[gloatlizard]

plz use at least aluminium or you won't be able to do nothing, if you want take an heatsink an solder on it a tube,it will work good
don't make tha base only 4mm thick,it won't handle good the load, use at least 1cm
good luck for your next bench

[dermedt]

Thanks guys for the fast answers!
We will do an another tube , made of copper , and based on 1cm thick support.

[marvt74]

Do you have any pics of your brass tube? What are the internals like?
Also what kind of load temps did you end up with or did you not try?

[dermedt]

Its nature , not polished (I haven't got any closer pics of it) . The wall of the tube was about -45 °C.
The load temps was about between -5 °C and 0°C .(P4 3.73 Extreme Edition/5300Mhz) .

[dermedt]

Here is a pic of the tube .Its not a good one , but i think You can see the inside of the tube.(The tube fixed on my DFi Ultra-D) http://img.tar.hu/dermedt/img/19228384.jpg#3

[afireinside]

Use copper on the next one and use acetone not alcohol. Do thqat and you're set.

[dermedt]

Thanks for helpin' !