The thing is the combination of a A10-5800K Trinity + HD 6670 (DUAL GRAPHICS) is faster than a HD 7750. Trinity doesn't run hot... If you are so scared of the 100W number, then go for a A10-5700K (65W)
My case is IN WIN BP655.300TB3L
300W TFX Psu + 3.0 usb front panel for $70. Just 0.5 inches...