Hi Buddy, I would not use computer fans they arnt very powerful I have like 8 in my pc but none in my grow room. you can buy an extraction silencer. but another option is sound prrofing that room you can use old egg cartons if you wanna make it yourself or you can purchase sound proofing tiles from amazon or ebay. its something im looking into aswell as i have 2 10 inch extractors which are very loud even when run on the lowest setting. best of luck buddy keep up the great work :)