http://www.newegg.com/Product/Produc...82E16822689012
Fastest SATA HDD on Newegg
Hard drives have been manufactured for over 50 years. The technology is so mature that there is very little separating the competition. The two things left that really determine speed is platter density and rotation speed. If you already have a modern drive, getting a faster hard drive really wont help that much. The two top performers are the 600GB Raptor and the 2000GB WD RE4.
The problem with those drives is that they cost the same as a 120GB Sandforce SSD while being much slower. Raptors have become an extremely small niche market for those that need an average amount of space with a slightly above average amount of performance for a high price. The RE4 redeems its high price tag for bringing average performance with a large amount of space.
If its really that big of a deal to you and you are already on a semi-modern drive, the only option is to go SSD. Even then not every game is even IO bound and you may not see a difference at all with your specific game.