Graphics could be better but there very expensive ATM

What budget are we working with and how much.

You could do with a new CPU and GPU tbh. But depending on your budget, you might be able to get away with one or both.

Alright, well first of all, add an SSD.

6GB GTX 1060 would be the minimum GPU you should be aiming for in terms of an upgrade, but with an R9 390/GTX 970 tier GPU, a 1060 is a sidegrade at best, so I'd really be aiming for GTX 1070/1070Ti performance. Which means, GPU upgrade is definitely off the table for now.

CPU should be fine, if you could find a used 4770k or 4790k and throw that in to the system, that would be a pretty solid upgrade for 144Hz gaming. 4790k's go for about £200 on /r/hardwareswapuk, and I think you could probably get one for $200/250 on /r/hardwareswap.

You could add another 8GB RAM. Luckily, DDR3 RAM can be had pretty cheap if you buy used, so that shouldn't be too expensive.

As said above though, we'd need to know your budget and currency to be able to properly help with finding parts instead of just giving you guidelines.

Adam wrote What budget are we working with and how much.

You could do with a new CPU and GPU tbh. But depending on your budget, you might be able to get away with one or both.

I can invest couple hundred quid.

~£500

I'm gonna say what everyone is thinking... it's just time for a rebuild man. Save the $500 and keep saving.