Well i think if it fits then it works. Just look what socket your motherboard have for GPU, and find card with that socket.
That's for the CPU, the socket has nothing to do about which graphics card fits on the motherboard.
I want to buy the cheapest possible graphics card that had 2 HDMIs so I can connect one to my monitor and the other on the TV.
How would I check what graphics card supports my motherboard?
The PC will mainly be used for entertainment (watching movies etc) and at times I may play SAMP on it.
As long as your motherboard has a PCI-e 3.0 16x slot any GPU will fit (since the mobo is more important towards CPU and wiring).
You would be good by buying a AMD GPU, a R7 260x will be around 120 euros or you can also go with a last gen product wich is about 80 euros, either way both provide plenty of horsepower.
Still finding a GPU that has 2 HDMI ports will be hard since most of them only have one and use display and DVI ports as primary connectors, you would be better off by connecting your monitor with a display port and the tv with HDMI.
Also make sure you have enough length room to fit the GPU in the case.