Well most of the cheap refurbished PC's that have been popping regularly have been SFF BTX boxes so very limited upgrade potential. This is full ATX and from what I can gather (but can't confirm) has two PCIE x16 slots among a few others, so there seems to be a lot of potential here.
I am not dissing it, it is not a bad deal, I am just pointing out some of its benefits and flaws. Yes slower hardware is a flaw, but the price is a benefit, and so on. Just want other people who are interested in this to make an informed decision about whether this hardware will suit their needs and such.
Like Anand used to say before joining Apple there is not really bad products in the tech space, its a question is this a bad product at this particular price
(now there are exceptions to all of this, and Anand said it himself, his whole quote was about is this servicing a market need, is this the best product compared to its competitors in a similar price point, and will customers pay this amount for this set of features.)
This is full ATX and from what I can gather (but can't confirm) has two PCIE x16 slots among a few others, so there seems to be a lot of potential here.
Yes it is dual graphics
http://h50146.www5.hp.com/lib/doc/manual/workstation/hp_workstation/504630_001.pdf
Many companies on their pro hardware have on their website service manuals like this for it is part of doing business where some people need instant repairs and thus their techs need to access this information. So must workstation hardware whether its from HP or Dell or Lenovo do this, you just need to know where to look on their website.
One of the things I like about Consumer HPs is they often also do this on their consumer lines which I see as a plus (now reliability of Consumer HPs, and Consumer stuff in general is another matter entirely). I think the companies have really nothing to lose by making this stuff available to the public and it can only produce good will.
Schematic Diagram of the motherboard
http://h30478.www3.hp.com/hpfr/attachments/hpfr/ArchivesAutresProduits/1892/1/workstation_z400_1.jpg
Real world picture of the motherboard
http://g02.a.alicdn.com/kf/HTB11l9....nt-Workstation-Desktop-font-b-Motherboard.jpg