HP Compaq dc 7800/HP L1710 Monitor No signal input (VGA)

try these
http://h30499.www3.hp.com/t5/Business-PCs-Compaq-Elite-Pro/hp-dc7800-5-beeps-problem/td-p/1142014#.VJYGUvXpAg


HP Guide to beep codes:
http://h10025.www1.hp.com/ewfrf/wc/document?cc=uk&lc=en&docname=bph07107
(see your machine spevcs for which BIOS you have if you don't know)

http://h30499.www3.hp.com/t5/Business-PCs-Compaq-Elite-Pro/Boot-problems-with-dc7800-CMT/td-p/1080736#.VJYHL_XpAg

and many more generated by searching the internet for "5 beeps hp dc 7800"

The second reference I posted is possibly the place to start
20.December.2014

how many time it beeps ?

try plugging into a different powerstrip

You should check the video cable and also try it with another PC since it is telling you that it is not sensing the video signals from your PC.

Basic LCD monitor and TV troubleshooting guide:
http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide
http://www.fixya.com/support/r7406380-tv_training_manuals
Failed TV and Monitors: http://s807.photobucket.com/albums/yy352/budm/

Learn about bad caps: http://en.wikipedia.org/wiki/Capacitor_plague

Capacitors kit: http://lcdalternatives.auctivacommerce.com/ he can make you a set of caps for you.

Or www.digikey.com just make sure to use caps with low ESR, 105c, high ripple current, long life rating such as PANASONIC FM or FC series.
Please leave rating if it helps.

It can be that your PC video resolution is set higher than 1024 x 768 @60Hz for the monitor to display correctly.
Spec: http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=c00485268&lang=en&cc=us&taskId=101&prodSeriesId=1130384&prodTypeId=382087



Try this per HP:
HP Business Monitors - What Do I Need to Do When the Message Sync out of Range Displays on the Monitor? ISSUE: What do I need to do when the message Sync out of Range displays on the monitor? When the video card signal exceeds the frequency allowed for the monitor, the following error message may occur: Sync out of Range SOLUTION: To avoid the message, lower the resolution or vertical frequency of the video card. Reboot the system and use the VGA mode to force the video card driver to lower its resolution. Follow these steps.

1. Shut down and restart the system. For consumer systems such as HP Pavilion desktop PCs, push the Power button once. For commercial systems such as HP business desktop PCs, hold down the Power button for five seconds.
2. Immediately after seeing the HP/Compaq logo screen, press F8 at system startup to initiate the bootup menu.
3. Scroll down to highlight Enable VGA Mode , and press ENTER .
4. After Microsoft Windows completes its bootup process, access the Display Properties and select a desired resolution, which is compatible to the connected monitor.

you can always try the windows me driver if hp does not have the driver on their support site

When you get it going, download Firefox and install
Wheever IE shows problems, use Firefox.
luciana44

If nothing was displayed on the monitor during the beeps then change the RAM stick(s)

Thanks

Bad Processor

it was my gateway,oooooooooooooooooops!!!