Can I use a molex to PCI-E adapter to power my graphics card?

[Guest]

Hello internet 😀

I'm about to buy another gtx 760 for my computer, but I realised my PSU only has 2x8pin PCI-E power connectors.
Will it be okay if I just buy two of these adapter thingies and just plug them in?
Of course I will distribute them over the different molex cains to make the power draw a bit balanced, but will my PSU handle it or can I have sudden shutdowns because of too much power draw?


Adapter example: http://www.tinyurl.com/kp3qabf


I hope somone can help me with this

Specs:
Intel i7 4790k (overclocked to 4,5Ghz)
Coolermaster Hyper 212 Evo (with it's original fan)
Asus Z97-a
Msi GeForce gtx 760 Twin Frozr 2GB (not overclocked)
2x8Gb of Crucial Ballistix Tactical DDR3 1600Mhz
Corsair CX550w
Corsair obsidian 450d (with it's original fans)
Samsung 840 Evo 250GB
Toshiba DT01ACA 2Tb , 7200rpm

 

[Woody1999]

The CX500M cannot power two GTX 760s. Even a high quality 500W wouldn't be able to. I recommend an 850W power supply at least for that kind of system.

Woody

 

[nottheking]

The short answer is that if a power supply lacks the necessary plugs... Often it's a sign that it'd be insufficient for others reasons beyond just that.

To be a bit more specific, the TDP of a SINGLE GTX 760 is 170w, and a 4790K at STOCK frequencies is 88w. Trying to run a pair of them with a stock-clock 4790K will total 428w; the rest of the components will add a little more on top of that.

Already, that'd be pushing the functional MAXIMUM of even an excellent 500-550w PSU. (the CX line is solid, though not amazing) And of course, that's still running a far higher load than you want: PSUs typically operate at maximum efficiency around the 50% load mark. This is also means that going beyond this point will seriously impact the unit's lifespan.

And even beyond that, there's the issue that using Molex->PCI-e adapters is far from ideal: a single Molex plug carries a single +12v wire, with a rated maximum capacity of 8.5a. In theory, this works okay for a 2xMolex->PCI-e 6-pin adapter, but when you get to the 8-pin plugs, this can start to strain its capacity. Especially since invariably, two of the 3 +12v pins are sourced to only one of those Molex plugs.