If you're really concerned with the power usage, you might want to look into a computer upgrade. an i5 4670k has a TDP of 84 W compared to your 1100t with a TDP of 125 W.
If you save up for just a new motherboard and CPU, you can probably use your old case, PSU, RAM, hard drive, and GPU. It will come out as savings for you in the long run, comparatively.
If you save up for just a new motherboard and CPU, you can probably use your old case, PSU, RAM, hard drive, and GPU. It will come out as savings for you in the long run, comparatively.