PC BUILD

The more cash the better, this is the price segment where adding a bit of cash gains you a lot more performence. I'm guessing that something like the $400 PC from here would be able to play CS:GO fairly well. However, I hope that your given budget doesn't include the monitor, keyboards and similar things. If you have 300 pounds and you still need to buy the peripherals (mouse, keyboard, monitor+headphones) then I don't think there's really a chance to fit in that into the budget...

The 500 pounds would be enough to get a good PC.

EDIT: You may want to check this subreddit and this site out. There are a lot of other cheap PC builds online available - you can google them. Important thing is not to cheap out on a PSU - the PSU won't affect a PC's performance, but a really cheap one made by a lesser-known company may damage your other components.

IMO the" most important part" of building a PC is searching for a few games you like and see their benchmarks. By doing this you know which GPU and CPU you want to reach your intended FPS target. For a game like CSGO a "cheap" GPU and CPU will be able to max it pretty easily in a 1080p resolution while for a game such as total war warhammer you will need a beefy CPU along side strong GPU to max it out at 30FPS.

In a very broad terms you will probably want a:

• CPU I5 @3.5GHz (or the amd equivalent)
• GPU 1060 (or the amd equivalent)
• 8 to 16GB DDR4 ram
• PSU (good one)
• motherboard (a good one if you want to OC)
• Case any that can fit the components

The reason I wrote intel and nvidia first is that they normally have better performance on old games; Generally speaking nvidia GPU beat AMD when the game uses directx 11 and intel beats AMD when the games are not optimized to use more then one core. If you intend to mostly play AAA you are probably better with AMD since the newest games use the hardware better.

What games do you want to play?

A £300 PC for CS:GO is perfect...

CS:GO is a million years old and runs on anything. This is why it is full of Eastern Europeans and Russians, even those cheap PCs can run it.
But if you really want to move to new AAA territory, then due to the insane increase in RAM and SSD prices (plus the freefall of the sterling), that entry level is closer to 600 GBP now. If you want to be budget, your best bet is probably a Ryzen 3 or Ryzen 5, with either a used Nvidia GPU or maybe a GTX 1060 or an AMD RX 570 (assuming you can find one, since due to being the best price/performance ratio card on the market, bitcoin farmers bought up most of the stock).

My second hand i5 Build under £400

https://uk.pcpartpicker.com/user/Rabit/builds/#view=JzNQzy

benchmark
http://www.userbenchmark.com/UserRun/5112222

that benchmark was great, especially for a second hand system!