I have a CM haf 932 advanced case in stock fan config,a hyper 212+ with only one fan,and my gpu is a reference 7970,and i cleaned out all the dust when i moved in with my sis 1 1/2 months ago,and the dust has already gotten really think,i have had less dust problems with a stock hp case lol.
Im not even mentioning about keeping your room clean.
What case do you have? Its all about having positive pressure in your case. Make sure more fresh air is coming in than going out soo with the pressure build up the air gonna "run" with all small holes that normally dust would come in. Of course dont make top fans as intake one due to gravity and big dust buildup.
here is my case http://www.newegg.com/Product/Product.aspx?Item=N82E16811119160 in stock fan config.
Is there a way i can change the current fans or buy some if i have to to fix this?
With 2x230mm fans as intake you should have positive pressure, but still i dont know if the 230mm on side have mesh do keep the dust of inside of the rig. If not buy one or do it MacGiver style (aka homemade mesh) by stealing your girlfriend/moms/sisters stockings and putting the on side panel. Not whole stocking, but the material will stop the dust from coming in. You need to clean them or replace them once in a time plus steal the black ones to keep them hidden if one of the females will be looking for their lost stockings. Its the word on the "street" with those stockings (i own Fractal R3 soo dont have a "hole" on side panel), but from what people say its working like a charm even if it sound crazy.
Filter all your intakes, either make some ghetto filters with some cut up pantyhose+magnets or buy some filters. Then make sure you have MORE intake fans than exhaust fans to create positive air pressure. I just realized Ookami suggested the same thing LOLOLOLOL.
Also, cover up your top fan holes. Regardless of fan orientation, it'll get super dusty.
If you have a carpet then you're just kind of SOL but filtering all your intakes and positive air pressure in the case will help a lot.