I have this idea for a gaming cluster and i wanted to see what people with a little more experience had to say about it. My idea was to have many(prob around 3-5) small mirco-atx boards with 3GB ram and a i3 processor and onboard graphics. and then one master node, full atx 16GB ram i7 processor and 2 Gpus. i would then have a linux os on top of that as the management os then have one(or many) machines that would be running what ever os. but my overall question is would the windows os get a performance BOOST and be able to run modern 3d videogames. also i would have the windows machine pass though one of(or both if possible) the GPUS.
Start at the mother end.
I mean LOOK at the games  you want to play.
Then plan a cluster that suits the games.
Find people who have already done it.
With GAMIN g, the game is everything. Hardware follows.
What you are trying to do is impossible.

A cluster like this works fine for a task that can easily be split up amongst several computers such as large mathematical calculations where each machine can work on a task for a while then send the result back to the central host.  Gaming on the other hand is real time and could not be split up in such a way.

Also THINK about the network connection between the machines, you will not be able to get a network connection fast enough to CARRY the raw data to and from the video cards.