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From ambient to SUB-ZERO

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Brolloks

Benching Senior on Siesta, Premium Member #8
Joined
Dec 26, 2006
Location
Land of Long Horns
Yesterday after many months of self convincing I made the leap from ambient based CPU cooling to sub-zero with dry ice. I must say the anxiety was soon replaced with feelings to relief and moved over to excitement followed by satisfaction.

In the next few posts I will share my experience with the good, the bad and the ... results

EDIT: Other insulation guides are listed here:
Meathead
CGS Drone
Miahallen
hokiealumnus (actual photos in post #79)
God_Tattoo

Watch this space...

Hardware :


Asus P5E3 Deluxe X48 motherboard


Intel E8500 CPU


2 x 1 GB Mushkin DDR3-1600


EVGA 8800 GTS
 
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The tools to go sub-zero

Dry Ice:

I made the mistake to ask the people behind the fish market counters if they sell dry ice and most of them did not know what it is. Dry ice (Penguin Brand) can be found in small cool boxes (looks like a box freezer) pass the cash registers close to the front door actually, Kroger and HEB sell it here in Houston as I'm sure many others.
Cost $1.19/lb. It comes in solid blocks each wrapped in plastic, some of the plastic bags have holes so wathc out for that. Best is to take a small cooler box with you to put it in, keeps it container and delays sublimation. I bought two blocks at aroung 6lbs each

2ngsqoj.jpg

Artists Eraser:

This stuff is not the same as molding clay btw, I did not know that. I was walking up and down in Michael's yesterday, as Hobby Lobby is closed on Sundays, and could only find the molding clay, tons of it. Untill I ask someone for the earaser stuff, it can be found where the pencil drawing aceessories are shelved. It comes on two sizes, go for the jumbo, I bought 8 packets just to be sure I had enough, I ended up using 3 and a bit. Cost $1.99 for the jumbo packet

29vchhk.jpg

Acetone :

Acetone, the heat transfer medium. At 1st I was worried bout the fumes and bad smell, it only smell when you put your nose to it and sniff it ;)

Can be found at Home depot in quart or gallon tins, cost around $7 and $16 respectively.

2lw89l5.jpg
 
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Board Preparation:

The board before applying the kneaded rubber (artists eraser)

I put the CPU in the Socket before laying down the rubber stuff, kneading the eraser for a few seconds makes it nice and soft.

23rabyr.jpg

Making sure you press the rubber securely around the whole socket area is key. I kept the socket latch open until I put rubber all around the socket, then closed the latch to squeeze the rubber into the socket area, so no air or moisture can get to the exposed electronics.

this is what it looks after about 15 minutes.

2hqt2mg.jpg
 
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Mounting the Pot :

No this was the most frustrating part of the whole experience. I could not find 5-6 inch threaded #6-32 bolts to replace the illogical two-part bolt design that came with the pot. So I struggled to mount the pot, get the insulation in and tighten the thumb screws.

Also because the put has such a huge base area it took me some time to make sure the base surface made good contact with the CPU's IHS, I had to work away lost of rubber around the base and pressed hard on the pot to make sure the contact was sufficient.

remember to put a match head size drop of the thermal past on before you mount the put

I also put some thick kitchen paper towel around the base to catch any moisture that might form due to condensation.

This is what it looks like after many attempts to mount the pot.

e6a87a.jpg



Ready to get started:

Putting the board and put on the Navig bench station and putting in RAM, GPU and HDD

System in still off .

sol89k.jpg

This is what the pot looks like empty

rj33pg.jpg
 
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Starting the cooling process:

To maximize heat transfer you need lost of surface area on the Dice, so I took a hammer and , with the Dice in the bag, crushed it until I got some small pea size chunks with lots of powder, I left all of this in the back and put it back in the cooler with the other solid block on top of it until I got started.

Because the pot and the acetone is at room temparture I decided to cool the pot down by scooping in about four tablespeens of Dice powder... waiting a few minutes and then I poured on about 1 shot glass of acetone.
This resulted in some smoke and lots of crackling/bubbling sounds which soon subsided. i could see some bubbles and the clear liquid after say 2 minutes. i added some more acetone up to the 1st ring.

Then I added a good amount of dice powder and chunks until about half way before I put power to the system and started up the rig.

I used the spoon to stir the dice/acetone slushy mixture. I had no issues with freezing at the bottom, it remained a clear liquid with small bits of dice. Also there was absolutely no smell of acetone at all.

33y5i7t.jpg

I used about half of the 6 lb bag and it lasted me a good 3 hrs.

After a while an ice ring formed at the top of the tube, the fan helped preventing some of the ice around the middle section of the tube where the two pieces of insulation meets up.


Temps experienced during runs:

These are some temps with the Koolance V2 at idle (stock voltages), idle at 1.76v on a 980X and load on the 980X with two GTX 480's.

Given that Dry Ice temperature is at -78.4 C I was very impressed with the efficiency of the pot. Temps never went higher than -72C even with a WPrime 1024 or Vantage run.

167l3fb.jpg

qodqpy.jpg

1z30a54.jpg


Some Lessons learned :

1. Once you are done with a session, discard the acetone and use fresh acetone when you start again. I tried to re-use the acetone and it got some water in after the ice-ring at the top melted, this resulted in the dice/acetone mix to partly freeze due to the water in the acetone. I could not keep the mix a slushy and my temps could not stay below 65C, it was also much more difficult to keep the temps stable. So use fresh acetone for every run.

2. I saw many people use fans around the pot, this actually causes ice that forms during the run to melt and water would run down the pot, let the ice stay there and let it pack on, it will not melt during the run, after the ruin pack some shop towel or kitchen towel around the pot to catch the water from the ice that melts.
 
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this looks crazy, where did u find out how to do this? also how much did it set u back? Somthing like this could be my next venture!!! XD. im excited, want to see some results!!!:clap:
 
All you need is hardware to bench, eraser, dry ice, and a CPU Pot, that being the thing bolted to the CPU.
That one costs $170+ shipping brand new (i have one too), but you can get perfectly acceptable custom made pots for $100-120.

This is one of the larger topics of discussion inside the team lounge :D

I just got started a couple months (and four sessions) ago, it's really fairly easy to get pretty good results. Really good results take more effort of course, but dry ice makes it easy to fly past all the air/water people!

You should join our benching team, we'll teach you everything you've ever wanted to know, and so much more.
 
OK guys, here are some results, very crude and rushed, I have a plane to Guatemala that leaves in a couple of hrs, I did this last night before I went to bed, needs a lot more work and I have pleanty to boards and CPU's to freeze:D:cool:
 

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Oh , and as I had no idea on temps, the bios got stuck at this, irrespective of the voltage or load, same with Coretem, could not get realtemp to work as I use a stripped down version of XP and missing some components

Front page article Ed? Would be good to get more people going sub-ambient around here. :)

For sure, hence the reason I try to write it up like an article, sort of ;) copy....paste :)
 

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Nice work so far. Need to see you pushing at least 5.6 when you get back home and shoot for more :)


I am curious what kind of millage you get out of 6lbs of dry ice. 1 session?? 10?? ;)

If you're benching a quad hard, and maybe a GPU, it's easy to burn through 30+lbs in one session. Crushing that much DI up is a huge pain, trust me.
 
6.4lbs lasted me four or five hours last friday, that's on a conroe dual core.
9lbs lasted about seven hours on a different conroe.

You can't really store dry ice though, at best you lose 10% per day, and that takes really good insulation.
 
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