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Old 07-19-2006, 09:24 PM   #1 (permalink)
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Default very strange... can anyone explain?

as you should be able to see from this picture:



i have 2 PSUs. the 2nd one powers all my case fans, cathodes, and optical and floppy drives, and 7900gt.

there is a 120mm fan in the front of the case, that is powered from the motherboard.

if i have the 2nd PSU on, and the main one off, so all the fans are spinning, and the lights are off, this 120mm fan turns on... even though the PC is not on...


please explain?


EDIT: did some more investigating.

the 120mm fan is powered when the 2nd psu is on, and the main psu is unplugged.

if the 2nd psu is off, and the main psu is on, the fans connected to the 2nd psu recieve power still.

if the 2nd psu is on, and the main psu is unplugged, the mobo power led is not lit up.


i think this has been happening ever since i got my 7900gt with the pci-e power connector, which runs off the second psu.

i really, really, dont get this. is power going through the GPU, to stuff the other side of the pci-e bus?

also, is this bad for my PC?
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Old 07-19-2006, 10:08 PM   #2 (permalink)
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draw out a chart with the two psus and the mobo and all the connections and stuff

then look at it and see if you can see the problem
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Old 07-20-2006, 02:54 AM   #3 (permalink)
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i don't know about that but your case is a mess
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Old 07-20-2006, 03:17 AM   #4 (permalink)
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well there is no need for a chart, the only "common" connection would be the GPU. the 6pin connector goes to PSU2, and the card is plugged into the mobo.
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Old 07-20-2006, 03:28 AM   #5 (permalink)
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i like the dell cases
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Old 07-20-2006, 03:34 AM   #6 (permalink)
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OK, i tried having the 7900gt on the main PSU, and it all works normally.

the thing is, the PSU gets very hot under full load, it only being a 305W, 17A @ 12v. i would rather not run it off this psu to be honest.
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Old 07-20-2006, 04:51 AM   #7 (permalink)
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yeah the temps in my pc have been sawing over the last few days what with this british heatwave.......

Id get a few cable ties and tidy those cables up, the air flow will be much better
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Old 07-20-2006, 05:23 AM   #8 (permalink)
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this is a common phenomena . you should make sure that both power supplies are running otherwise you will get excess current being drawn across the electrical traces on your motherboard/components. don't ask me to explain beyond that.

Quote:
yeah the temps in my pc have been sawing over the last few days what with this british heatwave.......
that sounds hilarious to me . i read an article about the other day and it said ".......temperatures up to 30 degrees.......". in summer i would guess 30 degrees would be the average temperature for me. the max recorded for my city was 48 degrees i believe!!!!!!!!!!
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Old 07-20-2006, 05:31 AM   #9 (permalink)
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Quote:
Originally posted by nitestick

that sounds hilarious to me . i read an article about the other day and it said ".......temperatures up to 30 degrees.......". in summer i would guess 30 degrees would be the average temperature for me. the max recorded for my city was 48 degrees i believe!!!!!!!!!!
thats so cheap, we get like 50-55degrees in the southern areas of israel on summer -.-

well, right now its more like 800c+/- but thats only because of the 'muslim' rocketwave, ROFL.

lol but seriously, you guys must be so used to having 15-20 degress there, those I get in the 'cold' winter days here lol...

-Jo.
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Old 07-20-2006, 06:18 AM   #10 (permalink)
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so does it matter i only one PSU is on say when turning on and then off?

i tend to turn the 2nd PSU on, and then the whole PC, and then turn the whole PC off, and then the 2nd PSU off.

should i be attempting to turn them on and off at the same time, or is it OK?


also, is the 2nd PSU powering the 7900gt or not? i dont want the dell PSU to power it, or it will end up breaking.
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