HD 7850 -> 130W
i3 2100 -> 65W
Motherboard, Hard disk, fans, etc -> 50W?
A peak of approx. 250W, almost entirely on the +12V rail.
CX430 V2 is rated for 336W/28A peak on the +12V rail, so your PC load is technically within limits.
BUT ..
1. This rating is for a 30 degrees celsius...