I have a Dell Inspiron 560. The VGA cable it came with was only 6 feet long and was too small for my needs. I purchased 2 different 10 feet cables and they each have the same issue. When the desktop attempts to go to sleep mode, the monitor does not turn off. Rather, I get a message that it cannot detect the VGA cord. Anyone ever see anything like this before? Not sure if the 3rd time is a charm and buy another VGA cord or if the distance is what is messing this up.

and last of all , we know how far VGA RGB/sync can go with good cables, 40meter easy but not Edid.

eDID comms (read sleep mode) uses weak signling called I2C transmitters/receivers.
these signals do not go far,
but if done right (most are NOT)
A classic spec is 25 meters. 82feet,imperial.
the problem is 3 fold,
the VGA CARD receivers the cable type and the monitors receivers.(and noise)
what your system can to distance wise on I2C lines is not known. (but 26ft sure)
but there is cool program (application prog)
that lets you see if the eDID data is working
called
EDID Manager (editors ,scanners ,etc)

one simple and safe (virustotal, safe)
is this.https://nirsoft.net/utils/monitor_info_v...

this program is very good and PORTABLE,(no install needed , yah.

now run 2 times.
first whit the working cable short.
then with failing cables longer.
the data must be there or edid is dead.
if you scan it and see the line there.
in the report.
see words , there (modes supported)
standby _suspend and low power.
mine new monitor shows, no,no,yes.

now you have a tool that allows you to
know many things,
what modes work, and if the cable fails for edid,

now my acid test.
I have headless, server that I have no monitor at all and run remote software in to it. to do that I have dummy DVI/ plug installed.
the program above shows INACTIVE.
and all lines are dead.
if you hide inactive (in view)
so that is what you get ,with a:
1:DEAD OR MISSINg monitor
2:bad cable. and last of all , we know how far VGA RGB/sync can go with good cables, 40meter easy but not Edid. eDID comms (read sleep mode) uses weak signling called I2C transmitters/receivers. these signals do not go far, but if done right (most are NOT) A classic spec is 25 meters. 82feet,imperial. the problem is 3 fold, the VGA CARD receivers the cable type and the monitors receivers.(and noise) what your system can to distance wise on I2C lines is not known. (but 26ft sure) but there is cool program (application prog) that lets you see if the eDID data is working called EDID Manager (editors ,scanners ,etc) one simple and safe (virustotal, safe) is this. https://nirsoft.net/utils/monitor_info_view.html this program is very good and PORTABLE,(no install needed , yah. now run 2 times. first whit the working cable short. then with failing cables longer. the data must be there or edid is dead. if you scan it and see the line there. in the report. see words , there (modes supported) standby _suspend and low power. mine new monitor shows, no,no,yes. now you have a tool that allows you to know many things, what modes work, and if the cable fails for edid, now my acid test. I have headless, server that I have no monitor at all and run remote software in to it. to do that I have dummy DVI/ plug installed. the program above shows INACTIVE. and all lines are dead. if you hide inactive (in view) so that is what you get ,with a: 1:DEAD OR MISSINg monitor 2:bad cable.

"Rather, I get a message that it cannot detect the VGA cord.)
if windows told you that, no version stated
but if yes, then that means the monitor ID is failing,
if the monitor OSD brain in the unstated monitor told you that error, usually in a black screen. (then in 10seconds self turns off, for screen protection)

no sync or signal?
no cables found? ,vga,dvi/dp/hdmi
or out of range.(mostly seen on relic monitors)
all of those means signals on the cable are wrong. (ANY)

also some video cards monitor the RGB video line drivers(phy) currents and if too high or low
shuts down the video card fast. (self preservation mode, as shorted cables do happen)

my Nivdia GTX650 does that. too.
then my driver for GTX tells windows that
and then windows tells you that.(windows pop up window)

Every tech that works with headless servers knows this and with KVM switches from H3LL.
vast KVM are edid DUMBB(sic).(fail hard)
and all users of projectors (OMG) oh my golly (gee).

in the old days, with CRT bulb monitors
one can burn up the phosphor screen if settings were wrong, SOME software still have protection for those relic monitors.


The PC scans the monitor to see
1:if it is there. (if not goes to low res mode or goes black screened. booted.)
2: what can it do. (all features supported)
3: and then shows you what valid resolutions you can use,
4: and to see what sleep modes are in fact supported, if none, then there will be NONE.

DDC goes back to the year 1995.
with over 8 revisions and
edid.2006. "Rather, I get a message that it cannot detect the VGA cord.) if windows told you that, no version stated but if yes, then that means the monitor ID is failing, if the monitor OSD brain in the unstated monitor told you that error, usually in a black screen. (then in 10seconds self turns off, for screen protection) no sync or signal? no cables found? ,vga,dvi/dp/hdmi or out of range.(mostly seen on relic monitors) all of those means signals on the cable are wrong. (ANY) also some video cards monitor the RGB video line drivers(phy) currents and if too high or low shuts down the video card fast. (self preservation mode, as shorted cables do happen) my Nivdia GTX650 does that. too. then my driver for GTX tells windows that and then windows tells you that.(windows pop up window) Every tech that works with headless servers knows this and with KVM switches from H3LL. vast KVM are edid DUMBB(sic).(fail hard) and all users of projectors (OMG) oh my golly (gee). in the old days, with CRT bulb monitors one can burn up the phosphor screen if settings were wrong, SOME software still have protection for those relic monitors. The PC scans the monitor to see 1:if it is there. (if not goes to low res mode or goes black screened. booted.) 2: what can it do. (all features supported) 3: and then shows you what valid resolutions you can use, 4: and to see what sleep modes are in fact supported, if none, then there will be NONE. DDC goes back to the year 1995. with over 8 revisions and edid.2006.