...active PFC ...
It seems as though the motherboard is a socket 478, while the CPU is socket 775.Basically if you were to get the old CPU to work you would need a new motherboard.
had to google that - its 20yrs since I studied this stuff
His CPU is more than likely a Northwood P4 HT CPU. That is a 478 Socket CPU bro.
He said if a E8400 would fit into a old dell...I thought the E8400 was a C2D 775?
The dell is my kids computer mine is a velocity micro with 775 socket. I was hoping when I upgraded the cpu on mine I could put it in my kids dell. But I will have to get another motherboard for them.