It should fit fine being shorter than the width of the motherboard. It is going to block the first PCIe X1 slot below it and that is it in conflicts.
OK, if that's definitely correct, then that's fine, since I don't use any of the PCIe X1 slots. It looks like it could be close to hitting the RAM slots though? Or does it just go over them?
Sorry, as you might be able to tell, this is my first computer upgrade :3
Can see no problems, it'll be close to the memory slots but will not interfere with them and may actually be short enough not to reach anyway.
Try to get a good named PSU: Antec, Corsair, Seasonic, Silverstone, XFX and OCZ are fairly available here in the UK. between 400 and 500Watts with a single 6 pin PCI-E lead will be more than enough. Avoid cheap 'high output' units as if they carried the Plague, they're cheap for several bad reasons.