you use your cpu for gaming or multitasking ? ( of course , you will ask why? )the answer is if you use it for multitasking the bulldozer is really aheavy bulldozer for it it may perform as i7 3770k in multitasking and the price is much lower than the i7 buuuut , if you will go for gaming ,then , you have to choose i7 3770k or i5 3570k
amd is not good company for gaming cpus , the bulldozer is worse than the hexa core phenom in gaming
what GPU do you have? is your GPU being bottlenecked by your CPU? if you don't know, download MSI afterburner, go to settings, monitoring, click on the things you want to monitor, then at the box below check "show in on-screen display". i would check GPU temp, FPS, mem usage and GPU usage. go play a GPU intensive game like crysis, BF3, metro 2033, etc.
if your GPU usage hangs around 80% or below, get a new CPU or overclock your 8150 or just buy a SB or IB CPU. if your GPU is 90-100% and you still have low FPS, get a new GPU. if you upgrade your GPU and it starts hanging around the 80s, overclock your CPU.
First; You haven't told us which GPU you have. So we can't answer if you would be better of with another GPU, instead.
Second; an overclocked 8150 can handle pretty much everything in a real world scenario. Yes, you would have more FPS with a similar GPU and some i5 2500k+ CPU, but you still get enough FPS with your current CPU.
That being said, it's most likely, even without knowing your actual GPU, that it's better to upgrade your GPU, if you want better game performance.
Yes the Ivy Bridges are better than 8150s, but considering you already have an 8150, no I think it would be foolish to spend the money on a new CPU and mobo, considering even in the 8150s diminished capacity, its still perfectly adequate to do anything.