HailStonE
Explorer
It's a risky business still you can try it on VX450 but it's not recommended,Hey one good thing you can get out of it is if VX450 goes kaput you'll get TX550M which will be good enough to handle HD6950.
If I recall correctly VX450 has a peak output of ~570w... Corsair deliberately re-badged it as 450w to provide ample head room, in reality it was a Seasonic SII 550w...