Ok, so after forgetting my username (don't you love it when you forget your username but remember your password? LOL), then finally remembering after what seemed like forever, I finally am able to log in again! Gidee~ Anyway, so I upgraded my computer's graphics card from some crappy old Radeon R7-240 that came with it (the computer's a custom build by the local computer shop) to a Gigabyte Radeon R9-270X. Of course, I loaded up The Sims 3 and pumped everything up to high just to find it even choppier than the R7-240 on low! I looked in the AMD Catalyst Control Center and saw my card was stuck at 300Mhz (going up to 450Mhz sometimes), when I'm sure the 270X is supposed to be at 1Ghz (or around that). What's going on??
Run some benchmarks and use the GPU-Z utility to monitor clock speeds. If the problem persists, try uninstall/reinstall or update display drivers. BTW, what are your hardware specs..? And is the card overclocked?
It means your card is faulty, it has a VBIOS issue. Check with the manufacturer for an update. If they cannot give you one, RMA the card.