Power supply enough for GTX 770/GTX 760/GTX 680

[ubieca99]

I have a workstation Delta 475w 80+ rated PSU, which a lot of professionals have told me over the years that it's pretty high quality with all japanese capacitors. Recently I have been offered these GPUs for cheap:

Reference GTX 770
Reference GTX 760
Asus GTX 680 DirectCU II (the extremely big 2,5 slot one)

I also use a non-overclocked 95w Sandy Bridge CPU and 8 gigabytes of RAM, along with 2 harddrives and a single 80mm fan. Currently I also have a GTX 650Ti (this is the part that is getting replaced).

The power supply has 3 12V rails:
1 for the CPU with 17,5 Amps
1 12VB with 18 amps
1 12VD with 17,5 amps

My question is will it be enough to power any of these three cards? I have entered my information into a power calculator and it shows that my maximum power draw will be 415/366/414W for the 770/760/680 respectively (although that is with the reference 680 which apparently uses a lot less power than the Asus one). As far as I know these calculations are made with the TDP of the components, or the maximum power draw possible, and that the actual power usage will be lower. Besides, I also don't plan to overclock.

Just to clarify that I'm not asking about an advice regarding buying a better GPU or a better PSU.

 

[Mark RM]

well the reference 770 and the 680 are basically the same card. I'd try it, it should work if you have the power draw balanced across rails correctly. set the power down to 80% if you can to reduce stress.

The worst thing that's going to happen is it doesn't work or the PSU switches off or you blow the PSU.

 

[ubieca99]

So according to some calculations 80 plus rating means that my PSU will continue to supply 82% of it's power at 100% load, which is around 390 watts.
The maximum power draw from the 770 + the cpu is around 320 watts + perhaps 50W at max for the rest of the system. I guess it should be okay considering that this is the absolute maximum.

 

[Mark RM]

No, an 80 plus rating means it will continue to operate at 80 plus conversion efficiency from AC to DC power, the max rating on your PSU stays the same if the PSU stays under it's max operating temperature.

In other words, a 1000 Watt 80 plus PSU would need 1250W at the wall to give you your 1000w of DC power.,

 

[ubieca99]

Even better then. You conviced me to go with the 770. I was ready to get the 680 since it was cheaper aswell, but then I saw that it's the Asus one ,which probably wouldn't fit in my case, and they rate it's TDP at 300 watts, 70 more than the reference 770.