Some dry ice questions for the masters

[computerpro3]

Hi guys...

Well, I saw a video of one of what I think was either MAcci's or Charlie's ancient dry ice adventures (looked like an rdram machine ) and it certainly got my attention. Too poor for phase change right now, and don't know how to handle ln2, so dry ice seems like a good middle ground. I want to basically give my chip a shot of NOS so to speak for some quick benchies. I want to see how high my 3.0C @ 4ghz on plain room temp water will go.

So now some questions.

1. What is the best method of benching with it? I understand you have to construct a copper tube with lots of copper mass at the bottom to hold temps, insulate the tube and componets, fill it with dry ice. But then in the video, the person poured a liquid over the dry ice to get the reaction really going. What is the best liquid to pour on?

2. How long can you keep benching on average for every pound/kg/whatever of dry ice?

3. How much dry ice should I get if I plan on like an hour of benching at a time?

4. I am in CT. Anyone know a good place to get it?

5. Are there any particular things I should do to enhance the copper tube design?

6. Exactly how cold does it get if done right. Is expecting 4.4-4.5ghz too much (i am willing to go to 1.8v and beyond on my chip...)


Thanks so much in advance, guys. Hope to begin building the tube with a friend soon....

[Crankster]

quite possible, you have it @ 4 gig already so 400-500 mhz extra might not be too hard

[charlie]

1) you need a liquid to transfer "cool" to the copper without freezing, try alcohol, the purer the better, ETHANOL goves best temps but simple 99% Isopropyl from grocery store does ok.
2) 10 lbs. lasts me 3-4 hours
3) ^^
4)??
5) Possible dimple the inside of the baseplate?
6) should be possible.

[computerpro3]

wow! The original Dry Ice Jedi replied! Thx guys. For the copper tube, I'm planning on buying a solid block of copper from dangerden, a copper tube from Home Depot or Lowe's or somewhere, and then solder them together with a huge solder gun. Would soldering work or should I braze it?

The dimple in the copper block sounds good, but I wonder, wound't it take away from the tube's mass at the bottom, which it needs for holding temps?


Thanks a ton!

[Rio71]

hi,
yeah, good tread.
i plan playing with di in few weeks. *beaker-build*

2) 10 lb = 4,5 kg for 3-4 hours... wow, this is long.
for benching... but what @ full load?
good isolation, vcore ~ 1,75v -1,85v, ~ 4ghz+ no hypertreading
here in germany i can bay 25kg (for 64 euro)
is this enough for around 2 hours of making an seti-bench?

2) how long for some benching but with ln2 ? around same time... longer...?