Tried reading through the whole thread...but it's really long 
Has anyone found any "cheap" 4U+ rack mount systems that can run 4-7 cards internally?
Has anyone found any "cheap" 4U+ rack mount systems that can run 4-7 cards internally?
The HP DL580 G7 can be found for less than 500$: https://h20195.www2.hpe.com/v2/getpdf.aspx/c04123267.pdf?ver=19+
+ 591205-001 HP DL580 G7 PCI EXPRESS RISER CARD
+ https://www.ebay.com/itm/10pin-to-6-6pin-Power-Adapter-Cable-for-HP-ProLiant-DL580-G7-and-GPU-50cm/141964325336