GPU power source question

joshd · 07-12-2006, 08:03 AM

when a GPU is plugged into a 6-pin power source, does it get 100% of its power through this, or does it still recieve some power through the pci-e bus?

i am planning on getting a 7900GT, but as the dell only has a 305W psu, i am planning on using an old 145W PSU for the GPU alone. i am assuming that it would power it ok.

i tried googling, but dont really know what to search for. i just get info that some need the power connector, not anything that shows how it actually works.

jseber1982 · 07-12-2006, 08:52 AM

so you are going to use a separate psu just for the gpu? First thing you will need to do is jumper a wire on the mainboard power connector on it so it will turn on. And does that psu have a connector for a pci-e card? And if not,, your planning to splice and solder wires to make it?

And another thing, from what i have read and heard on many forums... powering a psu up without it actually connected to the mainboard can damage stuff because the psu is built to have a certain load on it.

How new is your dell???
The OLD OLD dells use regular atx power supplies.. the old ones use proprietary power supplies.

The newer ones like the 620 and stuff use standard atx. At my work i put a 650w psu in a gx620 and use it as my lunchtime gaming box.

You also might want to look online to see how to mod an atx psu to use in a dell box.

Using 2 psus like that sounds really risky to me.. All you need is a small voltage leak and you could possibly loose both psu's, and other stuff like your gfx card or mobo.

joshd · 07-12-2006, 09:02 AM

mine uses an ATX, but i would rather not have to buy one, i cant afford a PSU AND a 7900gt.

yes, psus often have a minimum draw, but this will be satisfied by the GPU no problem.

yes, i will just stick a wire on the mobo connector. done that before, it works fine.

Ridlyn · 07-12-2006, 12:16 PM

Good luck, be prepared to get some extra cooling, because it's gonna get hot in those dell cases. With my stock cooling on my 6800 in a dell case got to over 100ºC, then i got my zalman vf700-cu and temps never go above 60ºC. I also had to add a pci slot cooler and a make a new hole for 120mm fan on the side.

joshd · 07-12-2006, 01:19 PM

@ Ridlyn

well, the side will be off all the time due to the wires from the 2nd PSU. i think it will be cool enough. i believe the 7xxx series dont run as hot at the 6 anyway.

the yellow one · 07-13-2006, 12:31 AM

just get a good PSU because if you're new to this you are all worry and crap and if did it wrong you could damage your computer. so just get a good one.

NosBoost300 · 07-13-2006, 01:31 AM

i'm sure the one you have will do fine.. i did the same thing with a 450 watt for 2 7900 gt's worked like a charm

P.P. Mguire · 07-13-2006, 01:38 AM

Undervolting certain things will end up in frying them in the long run. Never undervolt your cards or processor. Always have a suffiecient PSU becasue you will be paying for more than just a PSU ounce things start to cook.

joshd · 07-13-2006, 04:12 AM

well, a multimeter on my 12v rail already shows only 10.5v... i am not sure if this is correct, as i dont think a computer would even boot at that?

CrazeD · 07-13-2006, 07:10 AM

Make sure your multimeter is set right..

07-12-2006, 08:03 AM	#1 (permalink)
joshd Master Techie Join Date: Jun 2005 Posts: 2,131	GPU power source question when a GPU is plugged into a 6-pin power source, does it get 100% of its power through this, or does it still recieve some power through the pci-e bus? i am planning on getting a 7900GT, but as the dell only has a 305W psu, i am planning on using an old 145W PSU for the GPU alone. i am assuming that it would power it ok. i tried googling, but dont really know what to search for. i just get info that some need the power connector, not anything that shows how it actually works. __________________ E4300 @ 3.2GHz, Tuniq Tower 120 2GB GeIL Ultra 2900Pro - 850/999 - 3DM06 - 12,086 Gigabyte DS3 rev3.3 Audigy 2 ZS + HD595

07-12-2006, 08:52 AM	#2 (permalink)
jseber1982 Enterprise SMS Geek Join Date: Sep 2004 Location: Atlanta, Ga Posts: 879	so you are going to use a separate psu just for the gpu? First thing you will need to do is jumper a wire on the mainboard power connector on it so it will turn on. And does that psu have a connector for a pci-e card? And if not,, your planning to splice and solder wires to make it? And another thing, from what i have read and heard on many forums... powering a psu up without it actually connected to the mainboard can damage stuff because the psu is built to have a certain load on it. How new is your dell??? The OLD OLD dells use regular atx power supplies.. the old ones use proprietary power supplies. The newer ones like the 620 and stuff use standard atx. At my work i put a 650w psu in a gx620 and use it as my lunchtime gaming box. You also might want to look online to see how to mod an atx psu to use in a dell box. Using 2 psus like that sounds really risky to me.. All you need is a small voltage leak and you could possibly loose both psu's, and other stuff like your gfx card or mobo. __________________ QX6700, 680i SLI, 8gigs ocz memory 1KW PC power and cooling psu SLI 8800 GTX's, SB XFI

07-12-2006, 09:02 AM	#3 (permalink)
joshd Master Techie Join Date: Jun 2005 Posts: 2,131	mine uses an ATX, but i would rather not have to buy one, i cant afford a PSU AND a 7900gt. yes, psus often have a minimum draw, but this will be satisfied by the GPU no problem. yes, i will just stick a wire on the mobo connector. done that before, it works fine. __________________ E4300 @ 3.2GHz, Tuniq Tower 120 2GB GeIL Ultra 2900Pro - 850/999 - 3DM06 - 12,086 Gigabyte DS3 rev3.3 Audigy 2 ZS + HD595

07-12-2006, 01:19 PM	#5 (permalink)
joshd Master Techie Join Date: Jun 2005 Posts: 2,131	@ Ridlyn well, the side will be off all the time due to the wires from the 2nd PSU. i think it will be cool enough. i believe the 7xxx series dont run as hot at the 6 anyway. __________________ E4300 @ 3.2GHz, Tuniq Tower 120 2GB GeIL Ultra 2900Pro - 850/999 - 3DM06 - 12,086 Gigabyte DS3 rev3.3 Audigy 2 ZS + HD595

07-13-2006, 12:31 AM	#6 (permalink)
the yellow one True Techie Join Date: Mar 2006 Posts: 190	just get a good PSU because if you're new to this you are all worry and crap and if did it wrong you could damage your computer. so just get a good one. __________________ I am the yellow one.

07-13-2006, 01:31 AM	#7 (permalink)
NosBoost300 Hard Gay Nahalem! Fooo! Join Date: Nov 2005 Location: Bellflower, CA Posts: 10,076	i'm sure the one you have will do fine.. i did the same thing with a 450 watt for 2 7900 gt's worked like a charm

07-13-2006, 01:38 AM	#8 (permalink)
P.P. Mguire Banned Join Date: Dec 2004 Posts: 4,546	Undervolting certain things will end up in frying them in the long run. Never undervolt your cards or processor. Always have a suffiecient PSU becasue you will be paying for more than just a PSU ounce things start to cook.

07-13-2006, 04:12 AM	#9 (permalink)
joshd Master Techie Join Date: Jun 2005 Posts: 2,131	well, a multimeter on my 12v rail already shows only 10.5v... i am not sure if this is correct, as i dont think a computer would even boot at that? __________________ E4300 @ 3.2GHz, Tuniq Tower 120 2GB GeIL Ultra 2900Pro - 850/999 - 3DM06 - 12,086 Gigabyte DS3 rev3.3 Audigy 2 ZS + HD595

07-13-2006, 07:10 AM	#10 (permalink)
CrazeD Wizard Techie Join Date: Feb 2006 Location: Maine Posts: 3,158	Make sure your multimeter is set right.. __________________ Need website help? PM me!

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