You're probably missing some of the standard options you need to set in the BIOS. Enable above 4g decoding, set pci-e to 2.0 (at least 3 places in the BIOS where you should do it), disable all the controllers you don't need (audio, serial/parallel, etc).
Thank you I got it fixed! I just needed to set the pci-e to 2.0. 
Topic: [Noob][Help]8 gpu mining rig wont allow more than 3 gpu's (Read 136 times)
You're probably missing some of the standard options you need to set in the BIOS. Enable above 4g decoding, set pci-e to 2.0 (at least 3 places in the BIOS where you should do it), disable all the controllers you don't need (audio, serial/parallel, etc).
Is 4g decoding turned on in the Bios?
So whenever I start up the mining rig with 3 graphics cards it works like a champ on PCIE_X1 but whenever I hook up another riser and gpu the computer says the boot configuration is wrong. Thank you in advance.
SPECS:
Mobo: PRIME Z270-A
CPU: Intel celeron G3900
Psu: Corsair HX1200
Gpu's: PNY GEFORCE GTX 1060 x2
ASUS GEFORCE GTX 1060 x2
MSI GEFORCE GTX 1060 x4
Storage: Kingstone 120gb
SPECS:
Mobo: PRIME Z270-A
CPU: Intel celeron G3900
Psu: Corsair HX1200
Gpu's: PNY GEFORCE GTX 1060 x2
ASUS GEFORCE GTX 1060 x2
MSI GEFORCE GTX 1060 x4
Storage: Kingstone 120gb
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