no boot menu

[LA1978chik]

Hello everyone
I recently changed my video cable from DVI to HDMI thinking I might improve the picture. I found out that there is no difference in picture but only to video by doing this this since both are digital. (confirm?) I swtched back to DVI because I could not get my display to behave properly. I don't have the ability to adjust the screen to fit on my 37" LG.
Here is my problem. I have lost the boot menu. The screen which goes through the boot information with 3 or 4 screens before finally settling on showing my multiple boot options. The PC simply shows a black screen (no signal) until it boots into whichever default operating system I tell it to. (msconfig) I have 2 drive with 2 separate operating systems (W7-32, and W764) respectively. I cannot see any reason why changing the cable would cause this issue but I have been surprised by more silly things before.
I ask for any direction to similar issues that might have been posted here but which I haven't been able to find.

THANK-YOU

SOLVED !
I have 3 480GTX cards so when I reverted back to my original video cable, I just plugged it into the first card I could feel. Evidently I should have plugged it right back to where it came out of ??????????
My only question now is, Why?

 

[KSoD]

There are many reasons why. The first one I can think of would be that the system detected changes and that caused the boot menu to go missing. When you put the cord back in the original spot, the changes were undone and the system operated as expected.

 

[Yami]

I recently changed my video cable from DVI to HDMI thinking I might improve the picture. I found out that there is no difference in picture but only to video by doing this this since both are digital. (confirm?)

Confirmed. Video will be identical. The main difference between the two is that it's a lot easier to put sound through HDMI than DVI.