DVI-D cable connections

[cottage]

I'm having difficult getting my new Digital monitor to display correctly. It will not display the POST period (just prior to Windows loading). However, once Windows loads, everything works fine. As a result, I am unable to enter safe mode or to modify by BIOS settings. (I also have an analog input and it works fine with a DVI to Analog adaptor and an analog cable.)

I suspect that the DVI-D cable is the problem but need help. I have tried 3 different DVI-D cables and all have the same problem.

I have the DVI pinout arrangement diagram so I know what each pin is supposed to carry. However, all three cables have continuity on pins 1-23 but not pins 24 and C5.

I believe that there should be continuity on pin 24 but not C5. (I'd be certain about this except that I have 3 brand new cables that are all wired without pin 24 continuity.)

Can anyone confirm that pin 24 should have continuity and confirm that the lack of continuity on pin 24 will cause my problem?