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PC runs, but "no signal" msg on monitor

By dan ·
Recently, I built a home-theater PC (HTPC) with the following components:

Motherboard: ASUS A8N-SLI Socket 939 NVIDIA nForce4 SLI ATX

CPU: AMD Athlon 64 3200+ Venice 1GHz FSB 512KB L2 Cache Socket 939

Memory: 1GB (2x512MB) SDRAM Unbuffered DDR 400 (PC3200) Dual Channel

Graphics Card: eVGA GeForce 6600 256MB TV-out/DVI/HDTV PCI-E Heatsink Edition

Operating Sys: Microsoft Windows XP Media Center Edition 2005

HDTV Tuner: DVICO FusionHDTV5 Gold Plus

Monitor: Samsung HL-R5668W 1080p HDTV connected to PC via VGA cable

I'm running Microsoft Windows XP Media Center Edition (w/ all the most recent updates from Microsoft) and use a Samsung TV as a monitor via VGA cable between the GeForce 6600 graphics card and the Samsung TV.

Unless it's doing something, this computer is always in standby mode. I run an application that automatically wakes-up the computer and records high-definition TV shows for me. The monitor (Samsung TV) is usually powered-down while the computer is recording.

This system runs great except for one issue. Here's what happens:

- Computer running and recording as intended; monitor not powered-up.

- While the computer is running, I power-up the monitor.

- Monitor always displays "no signal" error message.

- Computer continues to run and record as intended.

No matter what I do -- including powering the Samsung TV up and down and unplugging and replugging the VGA cable -- the computer refuses to display anything on the screen. I'm sure the computer is running, because the TV shows being recorded are always OK, and I can "see" this computer from other computers on my wireless network.

It seems like the motherboard doesn't "enable" the graphics card to create a display signal when the monitor is off.

Any suggestions on how I can get the motherboard to "wake-up" the graphics card when I turn on the monitor while the computer is running?


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by BSchmidt In reply to PC runs, but "no signal" ...

Hmm, could be several things I guess. Without investigating the hardware more here are some things to try. Does the monitor come on when you first boot the PC? If so, check power settings in Windows and set the monitor to Always On (you can set a blank screen saver or just shut it off if you want). If it doesn't ever come up at all, even on boot, try a different monitor (just for testing) or even a different video card. Check the BIOS on the PC and make sure the video is set to default to your video card rather than AGP or integrated. If settings are correct, and monitor and video card are proven to be OK, it could be the system board. Anyway I'd check power settings, then video settings, then start swapping equipment to pinpoint the problem. Hope it helps.

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by dan In reply to

Yes, monitor comes on when I first boot this PC and Windows power settings have always been as you suggest. BIOS settings support video card; not AGP or integrated. I suspect the motherboard, too, but this PC runs flawlessly with exception of the one issue I described above, so I'm hesitant to rip it apart.

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I would guess your GPU failed

by Owning_Pheonix In reply to

Unplug the monitor from your pci-e graphics card, and plug it into the mother boards onboard one. If it works, replace your graphics card.

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by ctrservices In reply to PC runs, but "no signal" ...

Power down the TV and the computer (I know this is against the usual practice, but since there is no video...). Unplug the TV video feed. Reboot the computer with the display on. This should (if your system is functioning normally) push the display to your primary monitor. If you get this far, you can set the TV out as the secondary monitor in the Dualview mode (Nvidia Advanced properties).

Laptops can change which display the video shifts to by use of the Fn + another function key (usually F5). Don't know what to use for a desktop. Let us know what works.

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by dan In reply to

Sorry, I think you misunderstood my configuration. The primary (and only) monitor on this system is the Samsung TV. Connection is with a VGA cable. The TV is capable of 1080p display resolution using its VGA port, and it looks fabulous when it's not displaying the "no signal" error message. I can use all PC applications, surf the web, watch HDTV through the PC, etc., etc. The only issue with this system is the one described above. I should add that I can work around this "no signal" problem by NOT putting the computer into standby mode after I schedule HDTV programs to be recorded. If I leave the computer in run mode, I can power-down the TV, return later, power-up the TV, and have everything working as it should.

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by ewojciechowski In reply to PC runs, but "no signal" ...

To make sure we're on the same page, your display only stops functioning properly after the computer wakes up from Standby. When Standby is disabled, everything functions properly. Well there are a couple of things to look for.
1. Double check your refresh rate. I have seen video adapters lose some of their settings after standby and hibernation. You can test this with having another display hooked up.
2. It could be driver related. If this worked before, reload the old driver and look into NVidia's support about the new drivers. Or if you have not yet done so, try new drivers if they are available.
3. Finally try a different video connection if it is available. Don't use the VGA connection. It is possible that there is a flaw with the video adapter.

Hope this helps.

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by dan In reply to

Everything works flawlessly except when I power-up the monitor (TV) while the computer is running (recording a HDTV show). That's when I get the "no signal" message. I have triple-checked the refresh rate and it is always set at 60Hz, just as it should be. I have downloaded and tried different versions of NVidia's drivers and still get the "no signal" message on the monitor when I power it up while the computer is running. Your third suggestion is worth a try. I need to buy an HDMI cable after the holidays and substitute it for the VGA connection now in use. I'll let you know if it changes anything.

I really appreciate all the suggestions I'm getting here. With your help, I'm sure I can resolve this issue.

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by NZ_Justice In reply to PC runs, but "no signal" ...

sounds like your monitor operates like a KVM switch, the only way to regain the signal is to restart your pc with the monitor on.

One thing to do is install the monitor/tv drivers on your pc you should be able to download them from Samsung.

On the advance section of the display propertes on the monitor tab unceck the check box that says hide modes that only this monitor can display. reduce the refresh rate to about 60 hrz or even 50 hrz.

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by dan In reply to

I really appreciate your advice, NZ_Justice. I've contacted Samsung, but they do not offer computer-monitor drivers for my model HL-R5668W television, even though it does have a VGA connector.

Refresh rate has always been set at 60 Hz, so I left it there. Per your recommendation, I did uncheck that "hide modes" check box, but this made no difference. My TV still displays the same "no signal" error message if I turn on the TV after the PC has awakened itself from standby mode.

My workaround is to leave the PC powered-up all the time, but this seems stupid and inefficient, so please keep thinking about suggestions for a fix to this issue.

BTW, the vendor of my graphics card finally responded to my request for help on this issue and said that high-definition TVs are not supported as computer monitors because they do not adhere to the monitor standards. I dunno ... maybe I'll just have to live with this?

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by dan In reply to PC runs, but "no signal" ...

After months of ongoing frustration, I am pleased to report that my "no signal" issue has been resolved. The culprit was the VGA cable installed between the PC (home theater PC) and the monitor (Samsung 1080p HDTV).

Apparently, my problematic VGA cable handled the video signals well, but didn't support certain power-status control signals between the PC and the TV. Months ago, I suspected this cable, so I removed it and tested pin-to-pin continuity. All 15 pins "passed" so I dismissed the cable as a potential cause of my "no signal" problem.

Last week, having run out of new things to try to resolve my problem, I decided to buy two new VGA cables on eBay. The price was right -- only one cent for both cables. As soon as I replaced the original cable with one of my new 1/2-cent eBay cables, my "no signal" problem vanished -- and image quality is better than ever!

I appreciate all the suggestions I received here and hope I will be able to contribute something in the future.

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