Coldbug Drift?
 

Often I'll get a new CPU or mobo and get all excited when it doesn't have much or any coldbug the first time I freeze it, but I can never attain those temps again.

Any ideas as to why?

Most recent example:
980x: on Classy 762 seemed to cold bug in -135 range initially, but with later benches can't get much colder than -120. Same CPU on R3E benched at -150 initially without bugging (didn't try colder at the time), then started to bug at -135, now bugs at -127.

Is this an insulation thing? Mobo? CPU? Or is it simply tightening too tight? - Maybe I get more aggressive as I get more comfortable with a rig....... But loosening never really seems to help.

I've had this problem with 2 980x's, 3 i5 670's and a number of Bloomfields. A couple of the i5's would even go to "full pot" on the first run, then cripple me at the -130ish range thereafter.

Do CPU's just tolerate less cold after a while?

I seem to have the opposite "problem", at least during one bench session. The longer I bench the colder I can go without bugging out ?? As example, first CB may hit at -128C, subsequent one kicks in at -138C, then it jumps to around -158C

1. cpu degradation
2. cap degradation? ive yet to get my capacitance meter adn test this
3. cpu pot mount....

thats my list for now...

not goin with degradation as the cause....my theory lies in moisture as the cause.
If I take my eraser off and open the socket to the elements for a period of time, the cb seems to be what it was initially.

mounting pressure?

retraction and expansion?

Here's a read about Martian surface temperatures and solder.

http://trs-new.jpl.nasa.gov/dspace/b.../05-3335FN.pdf

Thanks guys. Very good tips. And you get the prize RM for the coolest article referenced on a forum. :thumbsup:

Gonna de-insulate before the next session and see what happens. With my half-decent fermi and a rockin IMC on the CPU, if I could get it really cold I think I could crush a few benches.

I discovered something weird the other day ... when running 2 sticks of ram I have no CB, with 3 installed it bugs at -120??

Which explains why I could run triple channel on my SS just fine, but could never run it on ln2.

i sense world records :D

Shammy posted that info on a new locked multi GT the other day. He had CB -150 with triple channel and no coldbug with dual channel.

Holy crap - can't wait to try it. I'm off next week. Almost time to play. :cool3: