What power supply/motherboard?

[Bobloiy]

Hi guys, my computer case is atx, but my motherboard is uatx, and power supply is internal atx. I'm confused, what form factor motherboard/power supply should I get? Thanks in advance.
Computer:HP Pavilion p7-1147c Desktop PC Product Specifications HP Pavilion p7-1147c Desktop PC | HP® Support

 

[BikerEcho]

You should take highly accurate measurements before buying anything to that case due to it's small size.
it says on the website that it is an ATX case, but i am not so sure that it can take a proper sized ATX motherboard. it is only 40cm tall.
What reason do you have to upgrade the motherboard?