Temperature Too High

When I'm just browsing the internet my HD4890 is at 78C and that's with overdrive on for 60% fan. When I play wow I have to turn it up to 70%-75% so it doesn't get to 90+. I haven't cleaned my computer from dust in over like 1 year, because i don't know how too. Might that be the problem?

It could well be,Dust can be one of the things that bump up the temps,It's easy to rid of,just unscrew the heatsink and blow out the dastardly dust,Or get a can of compressed air and blow it like that.

The dust is the worst thing for heatsinks.

There are some stuffs like hairdryer but so much stronger.

If any of your friend has one of them you can debt it for 15 minutes and use it.

And next time be sure your case has dust filters.

When I'm just browsing the internet my HD4890 is at 78C and that's with overdrive on for 60% fan. When I play wow I have to turn it up to 70%-75% so it doesn't get to 90+. I haven't cleaned my computer from dust in over like 1 year, because i don't know how too. Might that be the problem?

RedxSniper

If it's hard for you,you can pay a little money and let him\her to do it for you.