Year old machine suddenly no video. Motherboard posts.

So I have a home-built machine that's a little over a year old, and suddenly today the video signal went dead. When I restart the machine it seems to "Post" okay because it boots all the way to Windows (I can hear the Windows theme song chime thingy play when it boots all the way up), but no matter what I try, I cannot get the video to work.

To further complicate matters, I have an ASUS P6T motherboard which apparently has no on-board video.

Here's what I was doing when it happened:
I was in a full-screen program and I've seen this sort of behavior before... Almost.. Occasionally if I would get some sort of Windows system message, like an "New Update" was available for Adobe or Windows or Java or whatever, it would do the black screen, then hesitate, and then minimize the full-screen program and put me on my desktop so I could see the system message.

That seemed like what happened this time, only it never got to the desktop... It's like it got stuck in the black screen between minimizing my application and getting me to my desktop, and never recovered...

Here's all I tried:
- A different monitor.
- A different DVI wire.
- Taking out and putting my video card back in. (Including disconnecting the power connected to it.)
- A different video card - both in the same slot the previous one was in, and a different slot.
- Both DVI and VGA ports in the different video card. (Each slot with each of the two different monitors.)
- Checked all the wires and connections (internal and external) like 30 times.
- Unplugging and power cycling the CPU like 20 times.
- Unplugging and power cycling each monitor like 10 times.
- Moving my RAM around to different slots.
- Swapping in and out the RAM so that only one of my 3 DIMM cards was in at any one time. (Yes, I checked the MB manual to make sure they were in the right slots.)
- Unplugging any extra USB/Firewire devices. (Only the network cable, monitor, keyboard, and mouse are plugged in.)
- Holding down the "ESC" and "F8" keys during boot-up in hopes it'd somehow go into "Safe Mode" or the BIOS or something that would somehow kick the video signal on.
- Counting the "Beeps" from the motherboard at startup and trying to Google that for some sort of clue. (Apparently different companies use different meanings for different codes. For the record I have an ASUS P6T and I get one long beep followed by 3 short beeps, then a pause, and then another short beep a few seconds later. The funny/annoying thing is that even before this problem I would get a beep code basically bitching that there weren't additional hard drives installed or something (I could see the text), but I can't remember if it was the same beep pattern or not.)
- Removing the video card and booting up to see if the number of beeps changed at all. (They did not.)
- Hammering the "CTRL" key as it starts up with supposedly also tries to get into the default BIOS or something. (This seems like it might work, since I don't hear the Windows jingle when I do this, but I still get no video.)

I did a bunch of searching about this problem, and almost everything I read talks about the system not even "posting" but it seems like I am getting past that since I'm getting Windows to boot up, right?

The one thing I haven't tried yet is taking out the battery of the motherboard.. I tried, but I can't seem to get it out, and I don't want to start poking around in there with a screwdriver...

I'm out of ideas...

Motherboard: ASUS P6T
RAM: Corsair DDR3 6GB (3 x 2GB)
Processor: Intel Core i7 920 Processor
Video Card: NVIDIA GeForce 9800GT - 1GB
Power Supply: 850 Watt Thermaltake TR2 RX
OS: Windows 7 Professional 64-bit

Thanks in advance, this is driving me crazy!
9 answers Last reply
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  1. Well, you can stop with all the random attempts, as it's clear that we have clues that help narrow down the problem.

    - The fact that you NEVER SEE ANY VIDEO at boot up means that this is NOT a driver/windows/program issue. Trying to load defaults or such is not going to result in an improvement.

    -The problem could be in your BIOS I suppose, but I doubt that.

    You say you have tried a different monitor. Do both the monitors you have tried display menu items? Do they display an onscreen prompt for "no signal?" If you turn the monitor off, then back on while the machine is in Windows do you then see the "No Signal" message?

    Here's the way I see this right off, with the data you have presented. All your symptoms point to a basic hardware failure of the motherboard, but any such failure would surely result in serious errors and no POST. You are getting beyond POST clearly, and that says to me that the problem has to be non-critical.... but you have supposedly replaced all the parts that would be suspect.

    Hmmm. I do have a sudden idea, but before we go further please answer the monitor related questions.
  2. Yes, both monitors display menu items and both display the "No Signal" message even after powering them on and off (and even unplugging them for awhile and plugging them back in) while the system is already booted up to Windows.

    And both monitors work fine when connected to my other "work" desktop (which what I'm using right now to post here).

    Thanks for the tips and attention. Looking forwrad to hearing your other sudden idea. :)
  3. Given that you replaced the cable and tried a different working GPU, I think it comes down to two or three things.

    1. Some sort of motherboard failure that involves the PCI-E lanes but does not send a flag to the BIOS as an error.

    2. Somehow your BIOS has become set to display video on a different channel. I'm not sure this is possible on your board, but perhaps video is being sent to the PCI slots. Sounds unlikely to me.

    3. Insufficient power to the GPU, or out-of-spec power to the GPU. You could try a cable from a different rail on your PSU.
  4. At this point I'm thinking it could be a combination of 1 and 3... Like maybe the PCI-E lanes aren't getting enough juice. Doing a bit more poking around and asking friends, it sounds like maybe this motherboard's PCI-E lanes are provided power by the 8-pin cable, but the CPU and RAM get their power from the 24-pin cable. I guess it's possible one cable is getting sufficient power but the other isn't?

    Sadly, that cable doesn't fit into any other slots in the PSU, so I can't even try another socket.

    Seems odd to me that this sort of power issue could suddenly pop up after running smoothly for over a year. And the 850W of power I have should definitely be enough to power what I've got.

    Thanks for the help Proximon. I'm going to sleep on it, see if anybody else has any ideas, and then I guess if nothing else works I'll try a different PSU.
  5. Steve, Prox has it covered pretty well. You said a second video card does the same thing. That pretty much leaves the motherboard or power supply.

    And no, the 24 pin main power connector does not power the CPU. The 4 or 8 pin connector powers the CPU.

    Parenthetical comment: (I have never particularly cared for TT PSU's.)
  6. Hrm, so if it's not the 8-pin connector that powers the CPU, how do those work?

    I find it very strange that the machine will continue to boot all the way to Windows if something is messed up with the PCI slots... Either not getting a signal or whatever or not having enough power...
  7. SteveBDF said:
    The one thing I haven't tried yet is taking out the battery of the motherboard.. I tried, but I can't seem to get it out, and I don't want to start poking around in there with a screwdriver...

    That is actually the one thing that came to mind that WOULD help; I read through your list twice to make sure you hadn't mentioned doing it. Definitely try this. If something is wrong with the BIOS that's causing it not to recognize or look for a video card - which sounds like a definite possibility - removing the battery is the way to reset the BIOS to default settings.

    Most of the time, just removing the battery itself for about 15 minutes will do it; on some boards there's also a set of jumpers you can move and they tell you to also let the board sit overnight with no battery ... but I've honestly never needed to go to that extreme; just removing the battery briefly usually works fine.

    Pretty weird that something would happen to the BIOS out of the blue, though. Usually something like that happens when you're messing with settings or you're trying to do a BIOS update. Which makes me think that if the battery trick doesn't work, a hardware problem is likely; most likely the PSU, followed by motherboard, but further testing obviously needed.
  8. Thanks for the tip capt!

    I actually tried the batttery and jumper thing tonight. No dice.

    I'm JUST about to give up and try a new PSU. Though I stumbled across a post on the interwebz that seemed interesting. Basically said that there's been issues where the nVidia card power settings and Windows 7 power settings could "butt heads" and get screwed up. Seems unlikely that this would persists outside of Windows and even with a total battery removal BIOS reset, but I'm going to explore it some more.

    Also came across something about "interrupt" conflicts, but I have no idea what that means, lol.

    I still have a nagging feeling that it's not hardware, but somehow the PCI slot is "stuck" in power save mode or something. But maybe that's just me hoping I can avoid having to go through the headache of getting a new PSU and possibly MB.
  9. Well, it wasn't the power supply.. Got another PSU and got the same thing. Even tried another (3rd) video card. Same deal.

    However, a co-worker took my original video card and tried it in his machine at home, and it didn't work for him.

    Could it be possible that somehow the motherboard PCI slots "fried" and shorted out the video card as well?

    Next step is trying another motherboard at this point, but if my original video card is toast, I'm not putting it in the new MB.. So a new MB and new video card had better solve this issue or else I don't know what to do...
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