compared to what?
GTX 550TI + ? processor
vs.
i5 3570K
and what's the rest of your system and what are you doing?
Like if you have a 20gb harddrive and 2gb of ram; some would say, neither put in i3 or more ram or an ssd or even a bigger monitor to get your biggest gains.
Like for my mom, she's fine with a 8year old celeron computer. The biggest improvement for her is getting a bigger monitor so she can watch her youtubes bigger.
In some sense this is like Windows Experience Index. You need to improve your lowest score that meets your needs
The way your post is written, i5, because your system won't work without a CPU.