GPU Advice

i have an acer x3400 and currently have 2 gpu's but unsure which 1 to use

they are:

Geforce 315 512MB DDR3 and Sapphire HD5450 1GB DDR3

i would like to know which would be the better 1 to use, i have installed both and found that occasionally the 5450 "flickers?"

also and help on choosing a new GPU would be appreciated, it needs to be low profile as its a stupidly small case and i believe it has a 220watt PSU

 

try installing one then using some 3d Benchmarking software like 3dMark to measure performance. Whichever gives you highest marks is best

 

I'd personally go for the 5450 though a 220W PSU of questionable heritage would bother me. Check the stats out, as you can see, you're not far from the advertised edge of the PSU's power scale. I'd bet that's your issue.

As to half height cards, I have no experience with them. Are you sure you want to spend good money to fix your machine? I'd save my money and upgrade if possible to a new machine.