Case/PSU confusion

[imakesteaks]

Hi there.

Recently bought this computer.
www.bestbuy.ca/en-CA/product/acer-acer-aspire-desktop-computer-featuring-amd-a6-3620-ax3470-eb10p-ax3470-eb10p/10190541.aspx?

Didn't really have too much knowledge of computers at the time. Couple months later, found out about upgrading, got interested.

Thought this PSU would fit in the case.
http://athenapower.com/product/power-supply/flex-atx/ap-mfatx40

I, in ignorance, did not open up her computer to measure the physical size of the power supply for myself. The new PSU didn't fit.

Does anyone know of a case that would fit this PSU (designed for mini-ITX cases) and the motherboard (form factor is mATX) while supporting a full size GPU, preferably the Sapphire Radeon 6850 HD?

Any help would be much appreciated. Thanks.

 

[Cyberat_88]

That is why you make Steaks not computers. Stick to what you're good at and studied for. Everyone in the whole wide world think they can engineer a computer system that suits their needs. Thus hundreds of boards like this open up.
mATX power supply is 400W only and specifically build for All-In-One motherboards, it is not enough to power a full ATX with components and extra drives. Trade it for a full size ATX, get at least a 600W PSU with enough amps to cover what you put inside the case. Warranty decides brand.