We can confirm from the schematics(MacBooks) that all Intel Macs with Core i Series(until 2019 model) is using the hardware PCIe bifurcation strap. Some of them were strapped to x16, or x8 x8, or x8 x4 x4 depending on what they had been designed for. The same strap also works for iMac series, so far we have tested it on 2009, 2010, 2011, 2013 iMac.

X-Kepler has the same footprint with all GK107 based architecture:
Geforce GT650M
Geforce GT640M
Geforce GT750M
Geforce GT755M
Quadro K1000M
Quadro K1100M
Quadro K2000M

X-Whistler has the same footprint with several AMD Whistler lineup(small form factor):
Radeon HD 6750M
Radeon HD 6770M
Radeon HD 6490M
Radeon R9 M370X (MBP 15" 2015)

NevBolt-1 is designed for Thunderbolt 1 on MacBook 13" 2011 & 2012
NevBolt-2 is designed for Thunderbolt 1 on MacBook 15" & 17" 2011 & 2012

Contents in this video:

00:00 - Intel Mac similarities with Windows machines.
01:20 - PCIe Block Diagram explained
05:20 - Bifurcation switch location
05:44 - Conclusion

The X-GPU Project couldn’t get this far without the incredible works from these people:

OpenCore Team at Dortania
MacProUpgrade Group
@rossmanngroup
UEFITOOL Team : CodeRush@Nikolaj Schlej
VGA BIOS modders on MacRumors
@dosdude1
Acidanthera Project - vit9696
@pldaniels for flexBV
Hackintosh Community
Robert Feranec
MacBook Logic Board Repair group
MacBook Board Repair Community
and the list goes on….

Credit for Mac Pro 7,1 picture at 00:41 :
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