What to upgrade first?



If you want to do any kind of 144hz gaming, you would need a gtx 1070 at least. I would also slightly upgrade that power supply to 650 watts for future proofing, since that 550 will become 500 after accounting for capacitor age after a year or two. Other than that, looking good!

Good choice on keyboard for sure :)
 
Try to get a new CPU which will be worth step forward if your already own a weaker one.
if the CPU is weak so there's no use a high resolution monitor.
At least you may need for cores to roll with modern titles @ above settings

As alkatraz333.jh mentioned you may also need a better graphic cards if you want game on such high resolution. 1070 or RX 480 will be fine. if they still too much to afford just go with a R9 280 or GTX 960.
 


an r9 280, gtx 960, or an rx 480 would be worse than a 1060. If you want to go higher than that, go for a 1070

 

Thanks for the reply. I'm gonna get a 1070ti since it's not much more then a 1070, I want a very good psu so would the EVGA - SuperNOVA G3 650 W 80+ Gold be a good choice? And if I want to upgrade my cpu to "future proof" my build which cpu should I go for?