replaced mobo in XPS 420

I replaced motherboard in my 9 years old XPS 420 with the same TP406 model. However configuration of the machine is different from  one that arrived from the fatory. I replace DVD drive , processor from 2 core to 4 core and memory from 2  to 8 GB and operating system from Vista 32  to 7 64. Alter replacing mobo fans going on full speed all the time. Is it any way to control this? Also new mobo didn't  show graphics card ( slot showing not populated ) but graphics card is working.

ted