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Power hungery Peliters...

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New Member
Jul 24, 2001
Thanks to Rabid Bob Dole, I have finially got my secondary powersupply running. It is a 135watt ATX powersupply. Before placeing my 72watt peliter on my cpu I decided to test it with a FOP32 heatsink. After everything was in placed i truned on the 135watt powersupply and watch the ice form on the cold plate. I noticed that the fan on the heatsink and the powersupply fan was running slower then usual. Is this bad? The 135watt powersupply will only be running its fan and the peliter. How am i to know if the powersupply can handle the load of the peliter? Are there any equations for figuring this out, or should i just forget the 135watt PS and buy another 300watt to run with my existing 300watt powersupply?

TBird 1000/266mHz
256mb Musklin Rev 3 PC133 cas 2/2/2
30gig IBM ATA100 Deskstar 75GP
20gig IBM ATA 100 Deskstar 65GP
ASUS Geforce2 GTS 32mb DDR
Sound Blaster Xgamer live 5.1
3com ethernet card
Inwinn Q500 ATX w/300watt PS
if the fan is running noticeably slower, my guess is the psu is too weak. Maybe consider running only the Peltier from that PSU and the fan off of your other.

You'll probably get more responses out on the Cooling section, so I'm moving your post there.
You stated that you have a 135 watts PSU and a 72 watts peltier. Curious as I was I went to OC-shop and had a look at the specs of an 80 watts pelt. The details given were Imax=8.0A and Vmax=16.1V. After applying the formula I saw it used 128.8 Watts. This should be doable with your PSU and a fan.
However I don't know the effect on the power consumption of a pelt if you lower the voltage. It could very well be that the power consumption rises while the effectiveness of the pelt drops. As you are using a stabilized power supply, the voltage drops if you pull to much amps out of it. This could explain why the fan's speed is reduced. This is what I think (from my point of view as an elektronics freak) is happening at your setup. I suggest you go for a stronger PSU, I think 200 Watts will suffice as the voltage won't drop due to overcurrent.
plus, keep in mind that psu is rated at 135 watts under optimal conditions and with the mfg running the test themselves. With the above post, I'd guess it's not powerful enough to run that pelt too! 128 watts is right at the psu's max capability.
That small PSU isn't going to last long. What you need to check is that your PSU can supply enough amperage on its 12V line. I blew a 300W AT trying to run a 156W peltier off it because I was drawing 18A and its max on 12V circuit was 8A. Its hard to find a PC power supply that will give a lot of amps via 12V circuit. Thats why I'm running my pelt at only 5V right now. What sucks is the 3.3V and 5V can usually supply a ton of amperage, but not 12V that you need. Check to see if your PSU has a detailed power output chart on it.

*spazzed* (Jul 27, 2001 12:54 p.m.):
Or you could always give a battery hooked up with a battery charger a chance ;) Don't have to worry about amperage@12 volts :)

Eh, why don't you just use the batery charger directly? Even then, I'm pretty sure even the charger has a max rated current output. Hey, why not use a bunch or lower current rated AC/DC converters and connect their outputs in parallel? Thet way you get the same voltage, but with higher current 'bandwidths'!
*spazzed* (Jul 27, 2001 12:54 p.m.):
Or you could always give a battery hooked up with a battery charger a chance ;) Don't have to worry about amperage@12 volts :)

battery chargers only put out half wave rectification so you really dont get clean current and optimum performance from your pelt but it would work but the pelt probably wouldnt last a long