Because he needs to be poking around even more on his MoBo? It's a compact microATX build, meaning it's tight and cramped; plus it's custom hardware for HP...everything about it is going to be trying to make it more difficult for a DIY'er to get around.
---------- Post added 2011-05-07 at 07:31 PM ----------
I've never had to deal with HP tech support in particular, so they may very well know what he's got in there. I just know how tech support works in general and it seems odd that an off the shelf PC would have both onboard graphics and a PCI graphics card.