Great idle temps but high load on C2D?

Here's the situation, I have 1/3 hp Americold hermetic compressor that is huge and noisy, a large (about 9x9) steel condensor meant for drinking fountains, a RunMC/Under-the-ice stepper, and a big 9" dehumidifier fan on my direct die system.

I'm running propane for the refrigerant and I've tried overcharging/undercharging and the best idle cpu temp I can get with my Xeon3060 is about -48C but when I load it it jumps up to -13C. I know for a fact my evap needs to be lapped better but it's hard to lap the thing with the flexible hose brazed to it. I have about 2.5m of .28 cap tube as well. The propane I used was from a Bernzomatic torch bottle b/c the documentation for the bottle claims it has pure propane in the states (in europe it evidently has some butane in it).

Are my load temps higher than what they should be? My Opteron 148 @ 3.5 ghz only loaded this thing to -22C. The Xeon I'm running now is @ 1.6vcore and 3.8 ghz and I've hit a wall, can't get stable any higher b/c of temps and vcore.

Should I try shortening my cap tube? If so, how much should I take off? Like 6-8 inches?

What does this sound like to you guys?

I think your on the right track.. how much.. I would say reaserch (there are heatload and captube calculations/info to give you a definate range to work with)

Yea I initially did my calculations for cap tube length going by Gary Lloyd's tuning rules, and I went on the short end because I figured if I upgraded processors I would have the extra capacity.

After running it short (1.8m) for a while on my Opteron I lengthened it to 2.3-2.5m which dropped my Opteron's temps a bit at idle.

I'm going to sleep now but I'll shorten this up tomorrow to see what happens.

What kind of load temps should I shoot for with this thing? I figure I want a least -20C. Is that probably reasonable?

It depends on your CPU fequency goals and Vcore usage goals. (and plugging them in the heatload formula)

Well I shortenend the cap tube about 6 inches and temps are about the same, still tuning though.

I have 2 more things I need to do before the rebuild on this unit is finished, I need to insulate the last bit of suction line and also lap the evaporator.

Anyone have advice for lapping the evap after the unit is all assembled?

Are you able to measure the evap temperature at idle/load? If you are what type of Delta are you seeing?

I think you should be seeing a Delta of about 10c on your actual evap temps to indicate that everything is good with your actual system.

@ Idle the probe on the evap reads ~ -50C to -55C, the cpu being @ -45C.

@ Load the probe on the evap reads ~ -40C to -45C, the cpu being @ -15C.

greenmaji said:

It depends on your CPU fequency goals and Vcore usage goals. (and plugging them in the heatload formula)

Click to expand...

did you do this?

Just going by the different heatload calculators out there for overclocking processors, it looks like a xeon 3060 @ 1.6v and 4 ghz puts out ~ 180 watts.

Do a fourm search for the formula

These high temps are killing me so I did the heatload calculation and came out with 152 watts if I were at 1.6v and 4ghz.

That puts me at a longer cap tube length that I'm already at, so I'm going to add a good sized length of cap tube and if temps improve I'll keep it, otherwise I'll just slowly trim 4 inches off at a time 'til I get good temps.

Okay, I added about 18" of cap tube and idle temps are up from -45C to -38C, and load temps are up from -15C to somewhere between -5C and -10C.

Obviously this is too much cap tube, it is inhibiting system performance.

I'm going to go to the store and buy a couple more propane tanks (the torch propane tanks run out in about 2 - 3 charges for me), once I get back I'll hack off 4 inches and see what it gives me.

With a 1/3hp compressor (which in physical size and sound is huge) and large condensor, lots of insulation and subcooling and the system being tuned to 12C superheat I should be able to get the processor temp @ load to at LEAST -20C. I don't know, maybe my compressor is going bad.

Whats a good way of telling if a compressor is on the fritz? This one is probably 5-10 years old (since it came out of a used dehumidifier).

Here's some pics of it when I first tore apart the dehumidifier:







And also a pic of the fan I'm using which is SILENT and moves ridiculous amounts of air (top left):

Just a little update everyone, I did a little experimenting and the best I can get my processor to report for temps after tuning both cap and charge is ~ -16 on load.

Something else I found out when I had far too little refrigerant in the system is that when the processor's temp reports 17C, the separate core temps show 1C. Intel processors don't support Core temp readouts <0C and when the core 1 and 2 both showed 1C (and raising) the other temp readout was @ 17C.

So would this mean that when the processor is reporting - 16C that the core temps are really 10C to 15C lower than that?

BTW, evap temps @ idle are -60C and loaded are ~ -50C with the new charge/tuning. Cpu temps @ idle show -45C.