i have cheap 550watt psu......it has 18A on 12V rail.stats tell that it's enough psu but i have a feeling that my gpu is underperforming because of psu........my system runs fine in general but graphics card is not performing to it's fullest.,is it possible that gpu is being underperformed by psu,and i'm sure that it's NOT because of cpu or RAM or MOBO beacuse thay are high end in comparison to GPU.MY GPU is sapphire hd 5670....so can the psu do it?also don't consider that other components are sucking power because all components are of low power usage including cpu......my system runs fine but gpu don't perform to fullest actually is quite underperforming.....can it be the psu.......i'm asking this because i have heard that low psu also shows other symptoms but there are no other symptoms in my case......please answer.......