6i24 and boot / gpu

Hi Peter.

I have an existing 5i24 which is working fine.
I bought a backup 6i24 for redundancy a number of months ago, but have not used it as yet.
Today I was going to flash the 6i24 with the 5i24 bin file. Jumpers are configured to mimic the 5i24 board.
So I took the 5i24 out and put the 6i24 into the single lane PCIe slot.
Problem is that the computer goes through the BIOS flash, but then hangs on boot.
I have tried various other PCIe slots on the motherboard (single and multi lane) without success.
When I put the 6i24 board in I see LED's light up briefly, then immediately extinguish.
I put the 5i24 back in and the computer boots fully, and --readhmid reports correctly.
It is almost as if the computer thinks the 6i24 is a GPU and hangs there on boot because it isn't.
There are no BIOS settings to force the computer to ignore a GPU or to force it to use on-board graphics...
Peter, have you struck anything like this before, and do you have any suggestions?
Many thanks,
Marty.
 

I haven not seen this kind of issue but sometimes, motherboards with x4/x8/x16 slots
won't work with a X1 card. Also make sure that the 6I24 is jumpered for 33 Mhz clock
(and all jumpers match the default jumper positions in the manual page 4.

Thanks Peter and Tommy.
All the board jumpers are set to 5i24 settings.
There are no options in bios for pcie settings unfortunately.
They're is a 1x pcie slot on the mb but neither this, nor any other slots will allow the computer to boot with the 6i24 in situ.
As a trial, I have another (Windows) machine. That machine boots fine and the card is visible in device manager.
I think for now I'm putting it down to something to do with the computer, possibly mother board related.
One last question though, is there a minimum version of linuxcnc which needs to be used to allow the computer to recognise a 6i24?? Could it be something as simple as missing drivers?? IIRC the last time I updated was about 18 months ago.
Thanks!!