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Got that peltier and put it on my duron 750 and...

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yog

Member
Joined
Jan 16, 2001
Location
Tacoma, WA
Well I put it all together, and it wouldn't start! Nothing, no video signal, no POST, nothing! I waited an hour or so and started it again, it ran the POST but nothing else. waited another hour, and it gets ready to go into windows, but dies. So I go into the BIOS to check temps. It starts at over120F!! I was below this before. I wait and it stabilized at around 112F. So I try again, still won't go into windows, at 900 MHZ. So I turn it down to 750 and it takes a while, but it works. Well temps stabilize at around 114. Leave it on overnight and in the morning it stabilizes at around 104, which is good. Now I have turned up the heat in the room to 80 and the case got up to 95 and CPU went up to 125. Not too bad, but I'm running at 750, I should be at 900. Well now the room is cooling back down and I think I'll restart and trying to up the speed. Am I doing something wrong here? Shouldnt' it be cooler? I have a 85 W peltier sitting under a GlobalWin FOP 38 (now that I changed the fan). It is at 120 with the case at 93. Does this sound right? I was hoping it would be much cooler. Please help me! Why won't it go cooler?

Yog
 

LimeyGreg

Senior Member
Joined
Dec 20, 2000
Location
Los Angeles
That seems a little lite for cooling an overclocked Duron. Firstly you may not have good contact to chip, are you using a cold plate to spread the heat. If your pelt is not running before you power/boot up the I think your CPU is crapping out with the instant heat - the pelt isn't cooling it quickly enough to stop it overheating on initial boot.

Are you powering the pelt from your comp psu? If so what size is the psu? 85 watts is only the no load theoretical max it can pump - if you are under volting it that will be less, and it's not a linear relationship. If you consider at best it's only 70% efficient then you need at least 121 watts to run it, probably more if you are not running at the most efficient part of it's characteristic. 12v is not good, you need at least 14~15, preferably more - a separate supply with that 85 watt pelt is almost a necessity.

Finally, if your using air cooling then you need an HSF man enough for the job, it has to pump cpu heat and peltier heat - if it can't you'll end up with temps higher than if you just use the HSF by itself. Also, if it,s air cooled you'd better have good case ventilation or you HSF will not keep up - no matter how big the fan is that's strapped to it.

With peltiers you have to operate them at the right point, too little power ( low V and I ) will result in reduced efficiency and reduced cooling, too much power ( high V or I ) will result in excess heat generation within the pelt and a rise in hot side and cold side temperatures.

Check out this info on peltiers :-
 
OP
Y

yog

Member
Joined
Jan 16, 2001
Location
Tacoma, WA
Right now I am running it on case power and it is a 300 W PSU with a DVD, CD-RW, floppy, HD cooler, two case fans, and one slot cooler.

So I need to hook up a seperate power supply for my peltieer? How do I do that?

Thanks a lot for the help.

Yog
 

dimmreaper

Senior Member
Joined
Dec 16, 2000
Location
home
When it comes to AMD peltier cooling there are three popular ways to ga about it.

The wrong way: air-cooled underpower peltier running off the PCs PSU with an aluminum coldplate.

The right way: water-cooled 118W or higher peltier, running off an independant PSU, with a copper coldplate

The best way: water-cooled 156W or higher peltier, running on an independant PSU at the peltiers maximum voltage, with a copper of silver colplate.
 

AKDUDE

Senior Member
Joined
Feb 13, 2001
Yup, there is no way your gonna power that unit with the case powersupply. Yea its 300 watts but thats the INPUT wattage to the PS, not the output. Output is more like 100-800 (prob 80) so your lucky you havn't fried the duron yet.
I don't see you air cooling it, unless you have some serious fans in that case and on the heatsink.
A start would be to get a external powersupply. Something like a 12volt 20 AMp deal, or maybe higher? Im not sure how they rate the wattage on peltiers, like when they say its a 156watt unit, does that mean input or output? If its input then maybe you could get by with a 15a power supply.
AKDUDE
 

Hoot

Inactive Moderator
Joined
Feb 13, 2001
Location
Twin Cities
I have a Duron 600 that runs at 1000. Using conventional air cooling, for the life of me, I can not get it to go above 10x100. So, I bought the best Air Cooled HSF available. I did so, because I observed, more than once, while experimenting, that my chip overclocked at lower core voltages the cooler it ran. So, my reasoning was to cool it even more and that would allow me to break through the 10x100 barrier. I picked up a 50W peltier at the local electronics surplus warehouse, strapped it to my MC-462A and put it on the Duron with a 1/4" copper cold plate and Arctic Silver everywhere. Idling at 10x100 1.8V it cooled the Duron down to something like 15C as I recall, but as soon as I "put the spurs" to the Duron (P95) it shot right up in temp. As I recall, I backed out when the Duron core hit 50C and climbing. Lesson learned: A 50W peltier will not handle a Duron generating 50W of heat (Radiate.exe). Okay, the hook was set. The MC-462A had no problem handling that 50W peltier, so what about a bigger one? I purchased a 156W 50mm peltier and repeated the process. The Duron idled at 0C and rose to around 27C under load. To its credit, the MC-462A was still up to the task. It held the peltier hot side to 50C, well within the hot to cold maximum differential of 69C. I did manage to get the Duron up to 10.5x100, but that was not much improvement for all the energy I was expending to get there. I needed minus double digits C to get any substantial OC'ing gains and this was not the setup for that. I imagine a water system could have done better. I know for a fact that I was not clamping the peltier to the HSF with anywhere near the force specified for optimum performance. Adding insult to injury, the MC-462A, without the peltier, held the core temp to 33C under load. This, pretty much drove home the point about diminishing returns. If you intend to peltier, you better intend to water cool also, or don't bother. Looks like Hoot got a little too wordy again, making a simple point :)

Hoot