If he's budget-limited, then yes there is a call on occasion to mix older and newer parts. My 'new' build is a Xeon X3470/Asus P7F7-E WS Quad-SLI mobo/GTX-960s in SLI with some additional parts. The money you can save these days on used server grade parts is significant. A hex-core Xeon X5670 is $80.00, a motherboard for it is another $80 and it'll perform just fine.