For the record . Intel DH 4000 gives me avout 7kh/s on doge and my i5 3rd gen cpu gives about 10kh/s . But I noticed something weird. When I let the cpu run for about 4-5 hours on a pool it gave me 7-8 doge-s and when I let only the GPU mine on the same pool with another worker after 6-7 hours it gave me 0.6 doge-s.

Why is that big difference since the hashes are almoast the same ?

If I buy a video card for mining purposes can I attach it to a laptop through usb , or will it affect the mining ability ?