Will be installing a camera system in our food bank with 15-20 cameras. Have read the wiki on PCs for BlueIris and looked at some forum posts, plus have BlueIris running at our thrift shop (4 IPC-HDW5231R-Z cameras, Dell i5-4400). (It's running ~70% so I suspect it may not be configured properly, but that's a separate issue.) Looked for i7 optiplex or elitedesk PCs on ebay in the $400-$500 stated by the wiki. Found a Dell Optiplex 5040 i7-6700 for $449.99 and an Elitedesk 800 i7-4770 for $459.99. However, also found a Dell XPS i7-7700 for $420. I would remove the graphics card on the XPS machine. Is there a reason to go for the 8Gb Optiplex with the older processor over the newer 16Gb XPS? The Dells both appear to have capacity to add 2 WD Purple drives, but I can't find expandability info for the HP. Are any a good buy? Thanks.