Whats CPU is better for GAMING?

Solution
Since both of the listed processors are 2 core 4 thread the higher clocked I3 4170 would beat the I7 4500u. The problem is the I3 is a desktop CPU and the I7 is a CPU for a tablet or 2 in 1. They are different markets.
Since both of the listed processors are 2 core 4 thread the higher clocked I3 4170 would beat the I7 4500u. The problem is the I3 is a desktop CPU and the I7 is a CPU for a tablet or 2 in 1. They are different markets.
 
Solution
First of all, I want to apologize for my (very) incorrect answer. Didn't do my research before I answered.

The I3 would work for a desktop, and the I7 is made for compact mobile devices. I'd personally recommend an I5 if your budget permits it, as it'll give about the same performance as an I7 for less money.