JuZ0

Don't mix power sources. It will make you unhappy.

Use only one and don't have to wonder about stuff suddenly happening. If it's not enough you'll have to get a single bigger power source, either ATX as sangemaru wrote or SFX if it should be smaller. You may also have a look for fully modular ATX PSUs so that you only need to attach the cables to the PSU that you really need instead of that huge cable trunk you've usually got.

Yeah it sounds wiser to just stick to use one power supply.

My current plan is to use PE4C V3.0 with Nvidia Geforce GTX 680 graphics card. What is your opinion is the Dell DA-2 PSU sufficient for the GTX 680? I looked Graphics card reviews from techpowerup and it seems that the peak power draw of the GTX 680 during gaming is about 185-190W but during stress testing the power draw could peak as high as 230W which is more than DA-2 can supply.

I rather not use an ATX power supply so I try to stick with the DA-2. So I was wondering that I could undervolt/underclock the GTX 680 to reduce the power draw. It really does not matter for me if the cards performance decreases a little bit because of undervolting/underclocking as it still would be miles away from my Fujitsu NH532 laptops geforce GT640M-LE

Would the undervolting/underclocking be a easily achieved by software or does it require a BIOS mod for the graphics card?

Hello,

Just a simple question. Is it possible to combine multiple power supplies for PE4C V3.0 to get more power? For example could I put a 220W Dell Da-2 PSU to the 8-pin input and put a generic 12v 60W PSU to the round DC plug to get a combined power of 280W for the graphics card?