If the video board alone requires 325w then you definitely need to increase your PSU.

It is quite likely that your cpu, fans, hard disks, memory, etc. are going to consume more then the remaining 50w.

I had an FX2000 with EXACTLY the same behavior. I had a 400w PSU and bumped it up to 550w and the problem went away.

If the GFX board requires 325w I would suggest a minimum of 600w that would give you 275w for the rest of your system which shoud be sufficient.

Good luck