leburn98

You can buy a pci-e riser and place it in that area under the motherboard.
Rosewill RCRC-18001 Mining Card, Riser Card, PCIe (PCI Express) 16x to 1x Riser Adapter, USB 3.0 Extension Cable 60cm, 6 pin PCI-E to SATA Power Cable, GPU Riser Adapter, Ethereum Mining Riser Card - Newegg.com
Rosewill RCRC-17001 Mining Card, Riser Card, PCIe (PCI Express) 16x to 1x Riser Adapter, USB 3.0 Extension Cable 60cm, 6 pin PCI-E to SATA Power Cable, GPU Riser Adapter, Ethereum Mining Riser Card - Newegg.com
 
Small card goes into the pci-e x1 slot, and you use a regular usb 3 cable between the small card and the big card. The usb 3 cable connects only the signal wires from the pci-e x1 slot so you need to power the slot separately through that 6 pin connector.  It's a pci-e 6pin connector, but they'll bundle either a pci-e 6pin -> sata or pci-e 6pin / molex adapter with this.
The back is insulated with some rubber material , some even have double sided adhesive, so you can just put them below the board and you can screw your pci-e x1 card to the case.
 
eBay and Amazon and newegg is full of such cards, some will have straight sata or molex header on board so you don't need to use adapter cables (provided with the adapter)

 
 
example of similar boards :
Amazon.com: EXPLOMOS Latest PCI-E Express Cable 1X to 16X Graphics Extension Ethereum ETH Mining Powered Riser Adapter Card, 60cm Blue USB 3.0 Cable, 4 Solid Capacitors (VER 008S, 1-Pack): Computers & Accessories
 

 

BIOS isn't a problem, he updated it prior to selling it to me. He was running a 1600 btw.