motherboards dont require certain video cards so compatablity is not a issue.

As long as it has a pcie slot you're all good.

Ghaschke
How are you able to tell if a video card will be compatible with a motherboard. Sorry i am just getting into pc gaming and i want to build my own pc

If the motherboard is new enough to have UEFI firmware, it should be compatible with modern graphics cards. Older motherboards may lose compatibility after the 900 series of NVIDIA cards due to lack of UEFI compatibility. It is a case-by-case thing when it comes to that (depending on motherboard manufacturer providing necessary firmware update and/or video card manufacturer providing necessary firmware update to provide compatibility), so it's important to know whether your motherboard uses UEFI prior to making purchasing decisions.

Any will fit and is compatible if length is not the issue

GPU to Motherboard compatibility was a thing many years ago.  If you are buying new parts today... these are the things to consider,
 
The obvious
- AMD or Intel CPU, which one
- AMD or nVidia GPU, which one
- Monitor size, type, resolution, refresh, etc.
- Choosing the correct motherboard for your CPU
- Choosing the correct memory for your CPU and motherboard
- Choosing your storage options and fitment needs, SSD M.2 or 2.5", HDD, etc.
- Desired features for motherboard, number of slots and ports, etc.
- Aesthetics of case and components: LEDs, color of case and parts, etc.
- Mouse and Keyboard specs and ergonomics
Case fitment issues
- Motherboard size: ATX, mATX, ITX, etc
- Graphics card length and height
- CPU heatsink type and clearances
   including clearance over memory heat spreaders
Case cooling
- Layout and capability
- Depends on CPU / GPU power and cooling needs
- Fitment for AIO coolers
- Water cooling?
Power supply spec
- GPU requirements
- CPU requirements
 
I'm sure there is a lot more to consider...