what makes gaming fast on macs/pcs? Like the processors, RAM, that kind of thing. And what iMac would also be best for me? My budget is £1400 for an iMac at the most
itsme
well, I look at it like this. at the top, for 3d gaming your graphics card is the be all and end all. if you have a slow or underpowered graphics card, your cpu will need to do more work which could be better used on other things like controlling other hardware.
CPU speed in my opinion mostly affects the time it takes for games/software to load (also dependant on HD speeds but more on that later). This though is also dependant on how much ram you have.
The more ram you have, the less it needs to keep accessing the hard disk. when you run out of ram your pc will start using Swap space, which will grind your harddrive and slow things down considerably. bare in mind that ram is 1000's times faster to access than a hard drive. so the more your pc can use it's ram, the better.
when you double click to launch a game, the first thing that will happen is the computer will read the data from the hard drive and place it in ram. the cpu will then use what is stored in ram and then pass functions to other parts of your pc, the sound card, graphics card etc. and then you start to see/hear the game. once the game is running though, provided it has enough ram it'll run as fast as it possibly can. if it's hindered by having to read from the hard drive, lag, long loading times, frame rate drops will happen.
so really, to take the weight off the hard drive and cpu, ram is the thing to not scrimp on as well as your graphics card. the difference between an i5 2.5 and a i5 2.7 will be barely noticeable at all.
if you're fine with waiting a few seconds longer for loading things, but want a smooth gaming experience once it's running stick with that line of thought.
if you want blazingly fast loading times, going SSD will help, going SSD in a raid array will help even more, but your starting to add more serious dosh to the mix at that point.