I don't know anything about that brand, but something I think is common with lower end PSUs is over rating their max wattage. So it might not actually deliver 450W, and another thing is how "clean/dirty" the actual voltage is at higer load levels.
I've ran my 6950 on a cheapo 500W a few times, not something I like doing, so for my backup rig I'm going to get a new 1.
Here's too that are cheap but seem very good, I was considering these
Corsair CX430 V2 Power Supply Review | Hardware Secrets Corsair CX Series CX430 430W ATX 12V 80 Plus Bronze Power Supply 140mm Fan - DirectCanada Corsair CX Series CX500 500W ATX 12V 80 Plus Bronze Power Supply 140mm Fan - DirectCanada
can't find the reviews for that 1 I was using 2 weeks ago, but they're out there somewhere