[bowman1964]

well to be honest r502 is nice but really too much for what you get.too much cost involved.i dont even use it.we specialize in moble ac units which usaually use r12...r134a...r22.
now r22 will get very cold.boiling point is -40f @ 0 psi.mine will run down to -60f but i had it running in a hard vacuum.all depends on what you what to do.now the accumulator you will need to make for a small system like yours i havent heard of anyone using on on a small system.I made one but found it didnt do me any good.on a pc you are running under a load 100% of the time.not meaning the cpu is loaded 100% but that you are making heat all the time so the compressor needs to run full time.i have tried cycling the compressor on and off and there is no way the compressor can come back on and catch up to the heat load.to be honest on mine if i cut the compressor off for one minute i have to wait about 1 hour before i can restart it because the liquid runs back in the compressor after i cut it off.now if i didnt have mine cooling so low in the temps this wouldnt be a problem but running a xp2100 @2150 mhz @ -42c takes alot from a cooling system.i would stay with a capillary tube system no expanson vavle.the expansion vavle would not work as well on a small system.and all we use at work uses a expansion vavle so i would use it if i thought it would work better.