Make sure all your cables are plugged back in correctly. Most likely you jarred something loose when you put the new power supply in or forgot to connect a cable. check all your connections. Try removing any extra cards so it's just one stick of ram, one video card and nothing else.
So the computer powers on and the fans spin but it does not post.... This could be any thing.
First double check the power wires. You got the 20+4 main power connector.
Dont forget there is the 4 or 8 pin extra power wire by the cpu on the board.
Check that you got the PCI-e power wire in the gpu.
I would start by removing, blowing out with air, and reseating the ram. If that does not work,
remove, blow out, and reseat the GPU.
If those steps dont help i would reveiw the guides on what to do when a new build does not post.
Ok guys I think it is the graphics card as I tried the one from my other computer and could see something on the monitor. I also tried the one that I think is not working in the other machine and could not see anything on the monitor.
So my new question is what is a good reasonable price (cheap) grapics card for the above motherboard?
I do not use the machine for gaming.
I do use the machine for web browsing and would like something decent like the one I had. The cheaper the better unless it is worth spending a bit more on something that will last longer. No more than £80/£90 though.
if your looking for card that are less money then 560ti and 7770 and then 550ti. these have a little more gpu power then your old card. if your looking to save some money http://www.newegg.com/Product/Product.aspx?Item=N82E168...
is just an updated version of the card you had with the older 520 gpu that was replaced a few days ago with the oem version of the gt 630