Pc Projects?

So my dad and I are really into custom PC's, and I'm trying to look for a new project to work on with him. Almost a year and a half ago we built my PC and then a couple of months ago we changed the cpu cooler and all of the fans in my case (the corsair 500r), now i'm trying to think of a new project that isn't super expensive. Also to keep in mind that the computer that he plays on (he plays games like cod 2 and black ops 2) is around  7 or 8 years old. It can play those games cause we pu ta GT 610 in it which can play games at 720p with medium settings. So should we work on my pc or build him a new one. Some help here would be awesome!

Your PC is newer and therefore has newer parts in it whereas your dads is old with a cheap GPU.

One thing you could do i replace your dads Nvidia GT 610 with a newer, better graphics card if his CPU can handle it.

You could build a HTPC/Media server an athlon with a 7870 would be relatively cheap and would give your dad enough horsepower to play cod.  You could even make a steam box