PSU limiting performance?

[nflasky]

I finally got my gtx 780 working a few days ago after changing the motherboard to an Asrock z77 professional-m.   The graphics card seems to be working great.  When I use Precision X to monitor performance I notice that Power usage never reaches 100%.  Is this normal? The most it gets to is around 80%.  I was wondering if changing my PSU would improve performance.  I currently have a 600w PSU from HP but was thinking of replacing it if it's inhibiting performance.

[.Jay]

The easiest way i can answer is that no, its not going to alter performance.  Better power supplies will offer cleaner power but you do not want one too small or too large.  Many many years ago I rigged my machine to hook up some new video cards.  In doing this I used converters etc etc.  As I was playing a game, my computer started fragmenting and doing a bunch of weird things ... Then it went **BAM** That is the first time a computer actually scared the crap out of me (and I had a headset on ...and didn't blow anything out in the process besides the power supply).  With that said, that is what happens when overload a rail of a power supply.  Now on the other end, if you get too big of a power supply (lets just say 1200watt) and you are only using 400watts, then you efficiency curve is off.  Meaning, its probably not running efficient because your not pumping enough through the power supply.  Look at a power supply box and they sometimes show efficiency curves.

 

Easiest answer - If your running a video card that puts out a peak of 300watts, get a 600watt power supply, as you will be using a pure max of 500watts of the total 600watts.  You never want to use the total amount of what the power supply is rated at.  If you plan on getting two 780's then pick up a 900-1000 watt power supply (and install the second card) and you will be good to go.

[Darell3]

if your going sli in the future use a 850w psu. 600w should be fine, but change it, its HP branded :P and get a more better one like the ones from corsair.

[.Jay]

Ahhh - save your $$ and upgrade the power supply only if its old.  I have never seen an HP power supply (except one pulled from an old machine).  Did you reuse that power supply from a prior machine?

[nflasky]

It comes from and HP Phoenix, which is supposed to be a gaming set up

[.Jay]

It comes from and HP Phoenix, which is supposed to be a gaming set up

 

You are good - Keep what you have.  I was just wondering if you were using a 6yr old power supply or a new one.