Lol the i3 3240 is about 2-3x faster then the a4. The a4 is there to compete against intel celerons. i3 3240 won't bottleneck a 650ti while the a4 cpu is just to slow for any games. AMD need twice as much cores and higher clockspeed to get similar multithreaded performance to intel cpus. The a4-5300 is not designed for playing any cpu intensive game.
http://www.cpubenchmark.net/cpu.php?cpu=AMD+A4-5300+APU
http://www.cpubenchmark.net/cpu.php?cpu=Intel+Core+i3-3220+%40+3.30GHz
The a4 competitor of intel is the lower clocked celeron and the celeron still destroys the a4.
http://www.cpubenchmark.net/cpu.php?cpu=Intel+Celeron+G1610+%40+2.60GHz
If you are on a tight budget get this cpu but note in games that need 4 threads it won't be as good as an i3 but playable, (codemaster games benefit greatly with i3 over 2 core 2 thread pentium which destroys the a4-5300:
http://www.amazon.co.uk/Intel-BX80637G2020-Processor-SpeedStep-Technology/dp/B00B1MU7J0/ref=sr_1_1?s=computers&ie=UTF8&qid=1377873047&sr=1-1&keywords=g2020
http://www.cpubenchmark.net/cpu.php?cpu=Intel+Pentium+G2020+%40+2.90GHz