I think when he asks which cpu has a build in good PSU of 400+ watts he means the computer?
and he says when he change his battery's ram, he means his mobo's ram
it's the only thing that makes sense.
Now to OP,
You need to take out the ram that is on the faulty ram slot to make your machine work right now.
If you want to keep your i5 2300, then you need a socket 1155 motherboard.
the cheapest one is MSI H61M-P31/W8 Micro ATX LGA1155 Motherboard from Amazon.ca. if you are living in Canada
If you live in the US, then the cheapest one is Biostar H61MGV3 Micro ATX LGA1155 from Directron
you can take a look at this
http://pcpartpicker.com/p/Qv6Cbv if you live in the US.
Or
http://ca.pcpartpicker.com/p/pNNLrH if you live in Canada
Also OP, please keep your component name right
CPU = the small square thingy that go into a slot beside the ram slot on the big rectangular thing.
Motherboard = the big rectangular thing that your CPU and ram slot and PCIe slot go in.
Computer = the entire thing that is probably at your side when you stare at a monitor.
Case = The thing that everything goes into.
Monitor = A rectangular thing that you look at when you are at a computer.
Battery = a small circle that goes into the rectangular thing (motherboard).
PSU = A big thingy with many strings hanging out of it whose end you put into the motherboard.