Idle CPU Unstable

[Strida]

Let's just go over some basics here...

You've got a rotary compressor so that's not your problem. I'm assuming you're using your A/C's condenser so that's more than enough (size wise). You've got about 10' .031 cap tube. Cap in cap evaporator (maybe describe how you built it? How many caps/how big of holes drilled/etc.). Propane for refrigerant right? If you apply more load (higher vcore) temps skyrocket.

How long do you let it run for it to cool off? One of my builds took like 5-10 minutes to get down to the lowest temp, maybe you should let it run a bit longer?

Don't worry about what others' systems do. What you'll want to do for tuning without worrying about superheat and the such is get your processor running at it's highest load and highest vcore you feel comfortable with (basically make the processor as hot as it'll ever get), then add propane as the processor is loaded.

Get enough gas in there so that temps don't skyrocket when you add more vcore, load up prime95 (or orthos if you're running dual core). Watch temps via whatever program you have and add like 1-2 second bursts of propane to the low side and wait like 3-4 minutes between adding more to watch the temps. Temps will lower until they stop lowering where you'll want to give it one more 1 second burst of propane for good measure which will slightly raise temps but you shouldn't have to worry about overheating the compressor as much.

If this way of tuning still doesn't work for you then you might want to cut a foot of the cap tube and see what that does for you. If that doesn't work then the DIY evaporator is at fault... Just some speculation, but it might be filling with oil and the excess refrigerant is needed to flush it out.

 

[GunnerMan]

Thanks Strida. Well My evap is a 1" end cap coupled to a 1" to 1/2" reducer. A piece of 1/2" copper pipe about 1" long and then a 1/2" to 1/4" reducer. So basicaly it is a 1" end cap reduced to 1/4" via a few reducers. I drilled a hole in the side of the 1" to 1/2" reducer and put the cap tube in that. The evap is filled with copper wool as well. I will try your method of tuning and post back with what happens.

I do wait for it to get cold, I use the restroom grab a drink and go sit outside for a few. I come back and the whole thing still feels ambient. Kinda funky

 

[Strida]

The evaporator is DEFINITELY you're main problem. Get a new evaporator and you'll be sitting good and your temps will drop A LOT.

I thought your evaporator was more like this... http://www.xtremesystems.org/forums/showpost.php?p=697765&postcount=12

Basically cap tube into the middle/smallest tube, then it boils over into the next sized cap (which has holes drilled in the sides) which boils over then into the next largest cap tube, which has suction @ the top. Cap tube would be placed inside suction line as well.

The reason it takes so much refrigerant to get it cold is b/c the refrigerant isn't touching the base of the evaporator at all. It's just leaving the cap tube and then getting sucked up the suction line. You have to flood that whole evaporator before it would cool the base of the evap.

Do a test for me... Put your computer on its side (so that the evap base is flat instead of sideways) and run your system that way. With the evap you've got it still isn't going to work well but it should be a lot better.

 

[Strida]

Furthermore, don't try tuning the system as I said earlier with your current evaporator. You'd be flooding your compressor with refrigerant and also pressures would be quite high.

I bet with it the way it is, your accumulator/suction line gets quite cold but the evap doesn't right?

 

[GunnerMan]

Yes you are about right and I thought of that problem. Ill order a Chilly1 asap. The refrigerant probably only covers half of the base at most. Ill turn my comp on its side and try that test here a little later to see how it reacts. Thanks for your help!

 

[Strida]

Any results from tipping your computer on its side?

 

[GunnerMan]

Yes, it was a failure. My mounting system is about as redneck as my evap so when i turnd it on side it toally messed up the cpu contact. I agree like you said it all boils down to the evap. I will order one probably next week sometime.

 

[GunnerMan]

Well I did it, I gave up on my home made setup. It can't hold a good temp and is way to delicate. A Chilly1 2007 is ordered and on the way. I can't wait to get it mounted up.

 

[Strida]

Yay!

 

[GunnerMan]

Ok I got the Chilly1 installed and shes doing good. Very happy, only problem is its made things colder and the cold bug shows its ugly head. Anyway at 2.75 and 1.425 Vcroe it's load temps were 4C and idle was at -25 to -30C. I am browsing the net now to find some more results but it still seems like a large temp jump to go from -20 to 4C. This is fairly untuned because all I have is BIOS and cpu to load test and read temps. My lowside pressure is at about 3 PSI or so.