Hackintosh is superior to iMac, but slower! I don't get it?

[GazzaGreen]

Yikes. My new hackintosh seems smoother and faster editing in FCPX, but rendering is slower than my old iMac! It take my old iMac 29 mins to render a 30 minute timeline to prores, and it takes my Hackintosh 40 minutes! I have two AMD 280X cards in my Hackintosh, but it doesn't matter if I take a card out as rendering time is identical, so it seems having 2 cards makes no difference at all?

My Hackintosh is superior to the iMac, but rendering is quite a bit slower? I don't get it? What's going wrong?

See images attached, but here are the highlights of the components.

Gigabyte Z170X Designare
i7 processor (4Ghz)
32 Gbs Ram
Radeon AMD 280X 3gbs Card (X2)

iMac
i7 processor (3.4Ghz)
32 Gbs Ram
Nvidia GTX 680mx 2Gbs built in chip

 

[GazzaGreen]

Graphic Geekbench score is OpenCL Score 106921 so its not like its a slow graphics card (cards?). Again this score doesn't change if its just one card or two cards installed.

 

[GazzaGreen]

Imac geekbench score is... A lot less? <scratches head>