Quick question about dual PSU on 7800GT SLI

[afireinside]

I think my OCZ 520 is about to explode with all this load :eek: It smells like BBQ and I just locked to a black screen. I also think it may be holding my clocks back. I have an OCZ 420 I could throw next to my case to power the cards. Anything special I have to do? Plug cards in, glue a wire between green wire and ground, and flick it on before PC goes on? Will the cards draw a load on 5V or should I hook something else up as well? I'm afirad to stick my hard drives on it incase I screw up... I can't afford to toast all my data for higher clocks :p:

Oh and this rig runs 24/7 so is this safe?

[K404]

I`ve asked something similar and had a split response- some ppl think to have the cards powered by technically 2 PSUs (mobo is powered from PSU1, PCI-E slots are filled from PSU2) would kill the cards. I always thought that a common ground would be enough.

The new dual-core cards have a separate PSU slot for a dedicated wall unit. I dont know if theres anything else done to keep the card happy, or if thats just common ground as well.

Let us know what you dig up?

:)

Kenny

[afireinside]

It kills ATI cards but not nvidia. I know kinc and gocchin do it.

[mikeguava]

you most likely will not even have to connect the grounding on the second PSU -

In many setups ( including ATI) I have just connected the GPU without any on jumpers - and the #2 PSU will automatically turn and off with the PSU #1. Was a big surprise for me too...think the 6pin PCI-E GPU connector is getting grounded thru the PCI-E slot power and send message to PSU to go on.
Will NOT work with HDDs but GFX cards

[gocchin]

Yup I've got one psu powering the main board and drives and another powering 2 x 512 GTX and the gpu watercooling. I just jumpstart the gpu/water psu first then boot up the board. Kinc told me that the GTX's regulate their own power so it's fine :).

http://www.jpop.com/gocchin/dualpsu.jpg

[afireinside]

Ok I got it hooked up. Jason said wire the power on wire thing that you jump start with on the second PSU to a molex ground on the first. I did that and whenever I turn the second PSU on it spins up the fans in the PSUs and the fans attached to molexes on the first spin up. I'm afraid to turn the computer on ><

[afireinside]

Ok I turned it on and it hangs half way through GT1 of 3d05 at my 24/7 settings... What did I do wrong? I have my raptor, DVD burner, and 2x GT's hooked to the second PSU. rest hooked to the first.

[vapb400]

gocchin had drives on the main, did you try that?

[k0nsl]

I am using a Tagan 580W (EasyCon) for the motherboard(system), harddrives and DVD; videocard is powered by a OCZ Modstream 520W along with the pump and two fans.
I did not hardwire it or anything, I used the cable which came with my CM Stacker to contact the two powersupplies. The system certainly feels more stable now than it did before. Just knowing that the videocard is powered by it's own PSU is pleasing.

There really isn't much which could go wrong, AFI.

-k0nsl

[afireinside]

Gocchin cleared it up for me, about to give it another shot. Thanks! I had the HDDs on the second PSU because I didn't realize that the GT's used 5v as well as 12v so I needed a load on it.


Uh oh I jump started the second PSU and now I can't get the PC to turn on. I turn second PSU on for GT's in the back and it comes on and my main PSU comes on as well but the lights that indicate voltage don't come on. If I turn the main PSU on the lights on my DFI come on but it won't turn on. :stick:

Ok got it :D Air coming out of both PSUs is cold now and rails are rock solid. Bench time!

[saaya]

hmmmm weird....