Is it okay to use 1 molex from 1st pc's psu and use it in 2nd pc?

[Patryk Suchowierski]

Hi.
My 1st pc is using BeQuiet 1000W modular psu. I've bought new pc (2nd) and I need one more pci'e supplying cable which im missing. Would it be OK to take 1 molex from beQuiet, change it using molex -> pcie 6 pin adapter and use it in 2nd pc?

 

[Traciatim]

Though possible, it's more likely to be a terrible terrible idea. You can get molex Y adapters and Molex to PCI-E adapters. As long as you don't push the unit capacity the adapters are fine to use on the second machine.

 

[Patryk Suchowierski]

well, in my 2nd PC, i have 3 molexes only
In order to have 2 adapted pcie, i would need 4 molexes
So I will have to get myself
2x: http://static.erodov.com/reviews/guide/pci-e-connector/pci-e-power-connector-3.jpg
and
2x: http://image.ceneo.pl/data/products/9553276/i-manhattan-rozdzielacz-zasilania-molex-301503.jpg

do you think those can handle my card (which is radeon r9 270 and takes 140W)
My PSU is CoolerMaster b700 (http://www.coolermaster.com/product/Detail/powersupply/b-series/b700.html)

This PSU have 4x built in pcie cables, but they are used for another 2x radeon r9 270.

Total power usage would be something like:
3x 140W-150W = 450 (GPUs)
55-60W CPU

and it has 700W capability.
I hope I get it all OK and there shouldnt be a problems.
Do you mind say something about it?

Thanks for any advices.

 

[Traciatim]

I'm not sure I trust the coolermaster all that much, but it is a single rail and rated at being able to deliver 660watts on it's 12v line alone. In order to keep under about 80% of it's capacity you probably wouldn't want to push more than about 520 watts out of it or so. It seems like you'd be pushing it pretty hard, especially if you are using it for something compute related where your GPU's will be going full tilt and not some dynamic thing like playing games where they rarely stay peaked all the time. Though if it's a litecoin machine or something then the CPU isn't going to be doing a whole lot anyway.

Since the PSU's 12v plugs are all connected anyway it really doesn't matter what adapters are being used, stuff like that only comes in to play when you have a multi-rail PSU design where you want to be sure you don't overload a rail causing it to shut down.

What I'm really not sure about is why you would ever have a machine with 3 270's in it? Why can't you swap the PSU's with the other machine, or is it also using a very large amount of power? Why not sell the three and get a better set of cards instead?