Power supply and graphics card

[C4PTRI]

Ok so i got a Dell inspiron 660s and it's a slim case. I want to fit a 7750 or GT640 ( both LP's) into my case. I know it fits but i'm not sure on the power supply. It got a 220w power supply and basically *** everything up. I'm not sure if there is any spare watts for me to use. As i know here are the specs of my pc"

Model: Inspiron 660s
Graphic card: GT620(oem) runs on 30w
CPU: Intel i5 3450s 2.8 GHz
1TB 7200 RPM SATA Hard Drive
12GB of ram (11.9 usable)
Win7 ultimate service pack 1

If i can handle GT640 or 7750 LP tell me i can handle it and wont burn my pc up. If i cant, can you tell me what power supply i can upgrade to, can i fit into my case and also can my mother board handle it. THX

 

[ASHISH65]

For hd 7750 you need new psu for sure.corsair cx 430w is good for you.

 

[C4PTRI]

Sorry for the late response but I don't think the ps will fit into my slim case asi said