Fastest GPU/CPU pages

Short answer is 'the latest and greatest' the long answer is the 'best one you can afford to put in there', often the two answers will find a mid point that you can both afford to buy and run. Older gpu's tend to use more power, thus generate more heat, than the newer gpu's so if that's a consideration that factors into it too. Also whether you are buying used or brand new can also factor in as some of the older ones just can't be found new anymore and then you need to try and not get a mining gpu as they can be overclocked, gaming ones can be as well so it's kind of crap shoot unless you know who you are buying it from, or are willing to take the risk of buying one with a limited life span left in it.