Problem overclocking x1950xt

[Luke2]

Hi - I have HIS x1950xt with TR HR-03 cooler http://www.newegg.com/Product/Product.asp?Item=N82E16835109134
The temps are under 70C in full load
I use ATitool 0.26 for overclocking - but everytime I try to overclock the core for example - It's very unstable having to reboot the PC after about 2 minutes running the 3DView in ATitool(fuzzy cube)...
I did set the voltages higher - as you can see in the screenshot - the VGPU is on 1.5 and the clock is set to 681 (anything above won't even let me start 3dmark06) - it'd freeze right after about 3 seconds
The memory is set to 2000(effective) and I think I should have no problem running at those speeds

Other people reach 700 on the core smoothly...
So I was wondering what the problem could be and the only thing I could think of is that i son't have enough juice from my PSU - Even though I have this on it also - http://www.newegg.com/product/product.asp?item=N82E16817153037
My current PSU is Enermax NoiseTaker 485W Dual 12Vrails 33Amps Total
That could be the only problem I'm thinking of - or AM I WRONG ???
Please Help

Here is rest of the rig
I got AMD 64 3700+ San Diego @ 2.6
2x1gig Corsair Valueselect DDR400
85GB 7200RPM WD HardDisk
Epox 9npa+ultra
SB-24bit Live
DVD burner

Thx for replies

 

[Luke2]

plz admins delete this post - I decided to buy a new PSU
sorry bout it

 

[aspire]

I believe the x1950xt is rated to draw 30A off one 12v rail... thus it may or may not perform to its max in other situations.

Also, i have found that atitool sucks my ballz for overclockign and i am a devout rivatuner user.

 

[Luke2]

haha - well some ppl say ATitool is the best for Ocing some dont - I think it's just matter of opinion