Long vga cable - beware!

If your monitor shows "check signal cable" after you turn off your pc and it doesn't go to sleep mode, especially if you have upgraded to a longer vga cable, you might have a cable which did not fully implement all it's 15 pins connection.

Or, you might not even realize this, if your monitor indeed go to sleep - as 2 of my monitors shows different behaviour.

I found this out after purchasing 2 pcs of 5 meter vga cable - I'm thinking of placing my PCs further away, after having both PC's keyboard/mouse go wireless. 

First, the message "check signal cable" shows up on my 27inch Samsung monitor and it never goes to sleep mode. Also using this 'faulty' cable I can't setup the 1920x1080 resolution - the resolution just did not show up as a possible screen size selection - the max it can go is 1600x.  Using the original cable, there is no such message, and the system boots up to it's default 1920x1080 resolution.

I test it on another monitor, a ViewSonic 19inch. At first, the ViewSonic resolution is fine - it shows the default 1440x900. And shutting down the PC, the ViewSonic did show similar message, but goes to sleep mode after a while. However, on closer inspection, the image of the ViewSonic is a little blurr compared to the original cable.

At first, I thought it may be just a faulty vga cable, and since I purchased 2 pcs, I test the other cable - same result. A check on the volt meter shows 3 pins are not connected - same 3 pins on both 5-meter cable. I check  back on both the original vga cable, all 15-pins are connected.

In my case, it is pin 6,7 and 14 that are not connected : http://en.wikipedia.org/wiki/VGA_connector

So, unless you have a monitor that never goes to sleep when the cable is not right - you never know if you have upgraded to the wrong type of long vga cable!