If your talking of the on board GPU then it's a pretty good spec. But what do you want to do with your Ubuntu OS as far as graphics go?
Playing CSGO ( maybe something different in the future ) and Youtube.
No doubt its a good GPU as I can play UHD files fine with it. Its just for future reference incase I ever want to change it.
Another thing is the on board GPU uses some of my RAM, not that it's slow or anything because it's fast, just be nice to have a separate one.
Which job? DDR4 will top out at around 30-40GB/s bandwidth, if a program demands more than that you'll need to go for a graphics card with some variant or GDDR or HBM.
If the card manufacturer were to pick memory not compatible with the GPU it simply wouldn't work, so the only compatibility issue for you to worry about is whether it provides enough performance for the job.
Video playback is primarily done by the CPU and dedicated circuitry (AMD calls it UVD or VCN, nVidia Purvideo and Intel Quicksync), it's not notably affected by the general power of the GPU or the memory bandwidth.
So to play back future video formats you'd upgrade to a newer GPU that supports them rather than a more powerful one.
For gaming you may need both a more powerful GPU and more memory bandwidth, games can be limited by both.
Integrated graphics as a rule sits one step down from the cheapest recent card, which would be the RX 550 in this case. Older cards like an R5 230 will generally be slower than integrated graphics. They're kept in production to provide basic functionality for CPUs without integrated graphics or to drive extra screens
SO with a 500w PSU should I be able to run most GPUs ?
Some run off the Mobo and some run off the PSU is that correct ?
On Board GPU vs PCI-E GPU
If you use a CPU with a built-in GPU then you will be using some of your system RAM. However dependant on BIOS you can usually specify how much of the system RAM will be allocated to the GPU. If you’re a PCI-E GPUthen the RAM it uses is on the GPU itself. If you have two GPU cards, then it’s the RAM of both cards.
32 bit vs 64 bit
32-bit OS’s such as W7x86alloweda max of 4 GB addressable memory space. This meant if you put a 4 Gigs of RAM onto your MB and then put in GPU with 1 GB of RAM, your OS would only see 3 GB of RAM. But your using a 64bit OS and the limits are exponentially higher. That means you can have a high-end gaming machine with 16 or 32 GB of RAM and two GPU’s with say 10 Gigs of RAM each, all of your system RAM is usable, the GPU uses it's own memory capabilities. You do not see the limitations as in x86 systems.
Again you seem to be confusing things. Your PSU runs your system, the whole of your system, inclusive of your on board GPU or your PCI-E GPU, either or, you cannot have both. The PSU will only be good if it has sufficient power to run any PCI-E GPU(s) installed along with the rest of your system.
Sorry I meant that some GPUS have an extra cable which goes into the PSU, and some just plug into the mobo
Yes GPU's can derive their power from the MB and PSU directly , dependant on the design and power required.
Some of the GPUs look big and im thinking I'll have to take my LAN card out for it to fit or will it be ok ?
I know it will fit in the case but on my Mobo doesn't look huge
Sorry your post is confusing again. What are you trying to say?