Hi all, I've just joined in the hope of collating more data on quite
why the bifurcation mod described at
Badger707's github, issue #1 only half works for me.
I already had an M720q running as a home NAS & thin client but recently ventured into the world of home automation. Unfortunately I can't run two VMs, with each needing USB devices, because the M720q only has one USB root host to pass through. Pass-through only works at the PCI device level so passing through specific USB devices isn't an option.
The plan is to bifurcate the PCIe x8 slot into two, coupled with a dual M.2 riser card, providing x4 for the existing 2nd M.2 NVMe and an additional M.2 USB card.
The 2-resistor CFG mod seemed ideal except that it didn't seem to work on my M720q. I have also borrowed an M920q and the 2-resistor CFG mod kinda works except only for the M.2 NVMe.
Neither of my two M.2 USB cards seem to be enumerated on the PCI bus when using the dual-M.2 riser card.
However, the 2nd M.2 NVMe works totally fine in either slot of the dual-M.2 riser card!
So I'm assuming the bifurcation mod worked and the dual-M.2 riser card works also.
I just can't get my head around what else might be different or what to try.
Both Badger707 and myself tried the mod on our M720q boxes but it doesn't work because although the CPU supports 1x16, 2x8 or 1x8+2x4, the B360 PCH restricts this to only 1x16. See
Badger707's github, issue #2
Lenovo PCI whitelist unlikely to be the culprit because USB M.2 cards work with passive M.2 riser.
Any time an M.2 card is installed onto any of the risers, the corresponding LED on the riser is lit, so I'm assuming that it's not a 'presence' / PRSNT# / hot-plug issue.
To this end, I'm asking:
has anyone else tried this and could they maybe post their results?
My data so far is:
M720q - i7-9700T
BIOS version M1UKT74A - 11/14/2023
Motherboard IQ3X0IL rev 1.0 - 2018 04 03 (as printed on board)
| Passive M.2 riser in slot | Dual M.2 riser, slot 1 | Dual M.2 riser, slot 2 | Underside M.2 socket |
ASM3142 USB card | works | works (with slot 2 empty) | n/a (no mod on M720q) | |
uPD720202 USB card | works | works (with slot 2 empty) | n/a | |
NVMe SSD | works | works (with slot 2 empty) | n/a | |
M920q - i5-8500T
BIOS version M1UKT74A - 11/14/2023
Motherboard IQ3X0IL rev 1.0 - 2018 04 03 (as printed on board)
| Passive M.2 riser in slot | Dual M.2 riser, slot 1 | Dual M.2 riser, slot 2 | Underside M.2 socket |
ASM3142 USB card | doesn't work
(also 1st power-on hangs) | doesn't work | doesn't work | doesn't work |
uPD720202 USB card | works | doesn't work | doesn't work | doesn't work |
NVMe SSD | works | works | works | works |
ASM3142 M.2 USB card
uPD720202 M.2 USB card
PH45 rev 2.1 x8 to dual x4 M.2 riser card
Passive M.2 riser card