Q: if yes, will there be a performance drop? also, will i need to upgrade my PSU? Currently, I have 350W. my video card now is Radeon x850 XT, my CPU is AMD athlon64 3000+.
A: you will need a bigger power supply and your slot type needs to be pci-e. there are pci-e versions of the x850xt available, so disregard the above post in this regard. check your slot type and if its pci-e all you have to do is upgrade the psu. 450 should be fine.