That motherboard is not really ideal for overclocking. Also what kind of cooler is on your CPU?
To overclock a CPU properly you really want a decent mobo+decent cooler in your corner or you are going to hit your ceiling really quickly.
You aren't going to have access to the full range of CPU tweaking options on a B250 with a non K CPU.
There is a reason that they charge more for the 270 boards. Not saying I agree with it.
It sounds like your CPU is limiting you. I just read two different benchmarks and with the settings cranked up a but they are around the same as you are experiencing.
Dang sorry to hear that. You could try hitting up eBay. Some sellers ship to anywhere in the world and depending on which country you are in the added fees might actually be reasonable.
Probably not and do not cheap out on a PSU. It is actually dangerous to use no name or cheap PSUs. Could start a fire or damage the rest of your PC when it dies.
You could go into your device manager and see. Speccy should also tell you. Is the difference in consumption that different between the 2?
It would be wise to know which one for future formats\driver installs though.
If it was a PSU issue he probably would have seen some complete random restarts or BSOD. Sound like it is just throttling due to the over clock or due to an improperly installed\configured CPU cooler.
In my opinion the specs I look for range like this in order of importance.
144hz=1ms>Resolution>Gsync\Freesync>Extras.
In that price range you could snag the cut down Asus 144hz 1ms 24inch...
Sounds like a defect with the monitor. I wouldn't peg your hardware as the cause unless you have reason to believe so. I would contact customer support and see what they say.
If they have no clue post back here and I will do some reading.