muzux2 said:
Me no guru, but techie is right. Efficiency is basically about how green your PSU is and how friendly it is to your power bills. To provide 450W, a 80% efficient PSU will use around 540-550W. I am weak in maths and don't real have time right now so calculate the actual amount yourself :ashamed:
Now, the interesting thing is that most PSU achieve their rated efficiency at around 60 to 70% load and lower loads are less efficient. So, people who use a 750W PSU to power a rig that hardly consumes 250W, in fact are often at loss compared to the people who use a highly efficient Seasonic 350W for the similar rig.
That's an altogether different matter that those who buy 750W PSU have lots of dough to spare and hardly care about their power bills
As for the VX450W, it is a very able PSU that will power almost any single-GPU mainstream comp even if you have 2HDs, 3-4 cooling fans and a QX CPU. The great thing about this PSU is its solid components that can often deliver more power than what it is rated for. Of course, that doesn't make it a 500W PSU. Because occasional spike is one thing and regularly running it over its rated load is another.
Ideally one should aim at running their PSU at around 80% load.
hyeah: 
