2nd PSU

[GoLLuM4444]

I am thinking of getting a second PSU when I get my 2 6800 ultras as my current one is only 400W and is already powering 9 drives and just about all my motherboard voltages are as high as they go. Is anybody here using 2 PSUs or can tell me whether this is a good option or whether there's a chance I'll fry my computer?

Thanks,
GoLLuM

 

[nightelf84]

One 6800 Ultra at full load will consume roughly 250W. 2 6800 Ultra on SLI plus the 9 drives you're using, you would need at least a total of 650W with serious rails on each PSU. Not using double PSUs WUD fry your rig nahh...just kidding, but seriously, you wont be able to run your full rig with only a 400W, that barely cant handle your current setup.

 

[GoLLuM4444]

OK thanks for confirming that it is the sensible thing to do. The only problem is fitting it in my case which is already crammed with drives and the only obvious place (next to the motherboard backplate) is blocked by my mach2 condenser. I'm going to have even more trouble when it comes to watercooling the graphics cards.

 

[IIDX]

Mount it on top of the case XD

 

[ReconCX]

I'd hate to see your power bill at the end of the month!

You're gonna hafta look at a new case... and dual 400w or 500w.. a single 800w or so isn't worth the money, and also costs a lot to replace.

 

[wazzledoozle]

If your case is tall enough, tear out some of the shelves for 5 1/4 inch drives, and mount it there. Then drill a hole in the back of your case jsut big enough for the power supply cord, or pull it through an open PCI slot, OR you could drill a hole in a PCI slot cover!

 

[ReconCX]

drilling would make a mess, don't forget, you can't detach either side of the power cord to make the hole just a small round circle.... it has to be rectangular.. unless you cut the cable and piece it back together again.

 

[GoLLuM4444]

I might be able to fit it all if I get some bigger hdds and sell off all my old ones. Or I might sell my brother my Mach 2 and matching Enlight case and get a new Lian Li one with a full tower case.
The only problem then is fitting it through doors.

 

[wazzledoozle]

drilling would make a mess, don't forget, you can't detach either side of the power cord to make the hole just a small round circle.... it has to be rectangular.. unless you cut the cable and piece it back together again.

Well if you cut a slit down the bottom of a PCI slot cover, then bent it and moved teh cord in, then bent it back into shape you could get the cord through. WIthout using a slot cover the power cord should be able to fit through a PCI slot.

 

[fr33ze]

@ GoLLuM4444
I've been running two power supplies for about a year now and if you set it up right it works fine. If you want both power supplies to turn on at the same time then you will need to connect wire 14 on both psu's and wire 15 on both psu's ( see the following article http://www.techpowerup.com/articles/other/22). 14 is the green wire and 15 the one next to it.

one thing that is really important is do not connect the rails up, ie do not supply one component from both powersupplies as it will kill components. In this instance the motherboard and gcards count as one component so my sugestion would be to use one power supply for that and the other for all your drives and fans (thats what i did).

if you got any questions i'm happy to help.

@ nightelf84

One 6800 Ultra at full load will consume roughly 250W

just out of curiousity where did 250w come from, is that a guess or is that actually how much they use cuz it seems kinda high.

 

[nightelf84]

@fr33ze
http://www.anandtech.com/video/showdoc.aspx?i=2284&p=5

 

[fr33ze]

cheers mate, could just be reading it wrong but from what i can see the power consuption there is the whole system and not just the graphics card so it's not like the 6800 ultra alone will draw ~250w, stupidly overclocked cpu's barely draw that much and there no way a gpu draws as much as a cpu.

 

[GoLLuM4444]

@ GoLLuM4444
I've been running two power supplies for about a year now and if you set it up right it works fine. If you want both power supplies to turn on at the same time then you will need to connect wire 14 on both psu's and wire 15 on both psu's ( see the following article http://www.techpowerup.com/articles/other/22). 14 is the green wire and 15 the one next to it.

one thing that is really important is do not connect the rails up, ie do not supply one component from both powersupplies as it will kill components. In this instance the motherboard and gcards count as one component so my sugestion would be to use one power supply for that and the other for all your drives and fans (thats what i did).

if you got any questions i'm happy to help.

Yeah I set up 2 alright using a guide for a similar method whereby you also wire together 2 pins of the second psu to keep it on under no load (though that will probably never become useful). And I intended to run my 2 graphics cards off my 400W psu and my drives (which I shall try to reduce in number soon) and mobo off my 450W supply.

 

[fr33ze]

do not run the motherboard and then graphics cards off two seperate psu's. it'll blow things up. its really important that you power the motherboard and all the graphics cards from one PSU, i cant make it any clearer.

 

[GoLLuM4444]

Ok thx
Probably lucky I said that then. I haven't set it up yet thankfully. I haven't even bought the cards yet actually.

 

[fr33ze]

nw mate, let us know how you get on with it when it's set up.

 

[C&C Freak 2K]

It's probably a smart idea to run everything logically connected (such as the motherboard and the graphics card) through the same PSU. It only makes sense if you think about it.