500W Power Supply Enough?

[ta2]

I have a 500W Zalman power supply and I'm changing my graphics from a 8800GT to a HD6950 (the 8800 died ). Wondering if I'm gonna need to update the PSU as well, my system:

i5 750 @ 4GHZ (I've heard these take a LOT more power then they're OC'd roughly linear increase from TDP so ~143W)
4 HDD
4 sticks of DDR3
DVD (rarely use it anyway)
No expansion cards

I am planning to run the HD6950 @ HD6970 speeds which will allegedly increase power consumption from 169W to 202W. Would it be too much to give the extra 20% power to it like techpowerup have done here:

[nibbler]

Should be roughly ok imo, what voltage is the i5 at? That makes a big difference.

[ta2]

It's at 1.30V. Actually I turned it down to 3.8GHz a while back but I don't think that was because of the Vcore.

[Ulti]

It should easily run without any problems at all to be honest. Even if you were to overclock the 6950 it should be ok but it would be beginning to reach the higher limit of what I would load that PSU with.

[ta2]

It should easily run without any problems at all to be honest. Even if you were to overclock the 6950 it should be ok but it would be beginning to reach the higher limit of what I would load that PSU with.

Great, thanks both of you.

[nibbler]

1.3 vcore is very low, so that should mean lower power consumption than your typical OC. Nice work btw! Should be absolutely fine then.

[ta2]

Thanks! I think I got lucky with my silicon... I'm no expert, have only OC'd 4-5 chips ever. Although I have to give a thumbs up for Gigabyte's GA-P55-UD4 - very friendly even when you screw up, and also the Corsair H50 cooler.

[nibbler]

AFAIK, power consumption doesn't increase that much if the vcore stays reasonably low, though I could be wrong.