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[Solved!] Video signal lost; power button unresponsive


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#1
quetz32

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I'm having a problem where after the computer is on for a short period of time, the video signal goes out (i.e. the monitor goes black and auto-shuts off). If I shut the computer off (which requires flipping the power switch, more on that in a second) and turn it back on again immediately the monitor won't get a signal at all, which makes me think something might be overheating.

While this is happening, the power button is completely unresponsive; no matter how long I hold it down, the computer won't shut off (fans, lights etc. all stay on), so I'm forced to turn it off with the hardware switch on the PSU.

Initially this problem was accompanied by a burning smell, so combined with the video signal going out I assumed it was the video card. I have since bought a brand new video card and the computer is failing in the exact same way, so I'm assuming it's something else. I'm not 100% sure if I can still smell burning when this happens after replacing the video card, but if there is a smell it's now very faint. In any event I was never able to tell where in the case it was coming from.

Again, the fans and lights all stay on and the computer sounds like it's acting normally (in terms of component noises; I can't get the computer up and running to the point where I could test audio yet, although I'll check that if I manage). The DVD drive still opens and closes correctly, even though the power button is unresponsive.

Personally, I'm out of ideas. I'm 95% sure it's not the video card unless the new one decided to fail in the first half hour the same way as the old one. I doubt it's the power supply, since everything seems to stay on and the DVD drive still works, but maybe I'm wrong. And I have no idea how to distinguish between problems with the processor, motherboard or memory - I'm not completely tech illiterate, but this is the first time I've seen this and I don't have any older parts to swap out and test with.

Any ideas?

Edited by quetz32, 09 May 2012 - 03:17 AM.

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#2
iammykyl

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Gday quetz32, Posted Image

I will start off with some questions so that some basic informations is available for others who come in on the topic.

Is the PC Branded, ie Dell, HP?, please give brand and model number. or, home built? please give full specs.

Will the computer boot to the BIOS?

Before touching anything inside the computer, Unplug from the mains, take anti static measures by briefly touching a bare unpainted part of the case.
Does you pc have an internal system speaker like this, http://cwc-group.com/8ohm.html the beep codes can give a good indication of where the problem lies.

My first look would be the PSU, Even though it runs the fans, HDD and sounds like it is powering the system, there could still be a fault. not delivering enough power to the Mobo/CPU or not enough power to the video card. If you video card only requires one power connection and the psu has 2, try swapping around as the lead may be faulty. If a swap in known working one is not available, A local PC store would be able to test it for you, often free, give them a ring to find out.

Edit, spelling.

Edited by iammykyl, 02 May 2012 - 08:18 PM.

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#3
quetz32

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Hi iammykyl, thanks for the help. It's a self-built computer; I'll list the parts and link to the Newegg pages I bought them from if more information is needed:

Motherboard: GIGABYTE GA-MA770-UD3 (full: GIGABYTE GA-MA770-UD3 AM2+/AM2 AMD 770 ATX AMD Motherboard)
PSU: Antec Basiq BP500U (full: Antec Basiq BP500U 500W Continuous Power ATX12V Version 2.01 Active PFC Power Supply)
Processor: AMD Phenom II X2 (full: AMD Phenom II X2 550 Black Edition Callisto 3.1GHz Socket AM3 80W Dual-Core Processor HDZ550WFGIBOX)
Memory: OCZ 2x2GB (full: OCZ SLI-Ready Edition 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model OCZ2N800SR4GK)
HDD: WD Caviar Black 1TB (full: Western Digital Caviar Black WD1001FALS 1TB 7200 RPM 32MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive -Bare Drive)

Old video card (since removed): HIS Radeon HD 4890 (full: HIS H489F1GP Radeon HD 4890 1GB 256-bit GDDR5 PCI Express 2.0 x16 HDCP Ready CrossFireX Support Video Card)
New video card: XFX Radeon HD 6870 (full: XFX Double D HD-687A-ZDFC Radeon HD 6870 1GB 256-bit GDDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support Video Card with Eyefinity)

I've had the computer for three years (not counting the new video card, which I just got) and I haven't had any problems before now. The video cards both require two power connections and unfortunately I'm pretty sure that's all the power supply has.

The computer definitely boots to BIOS, assuming the monitor gets a video signal at all. It will continue to boot to Windows (again, if the monitor is showing a picture). I'm not sure what happens when the picture cuts out, i.e. if anything is still running or not. I don't know if the motherboard has a speaker, but I definitely don't see one. The computer will definitely always reach Windows though, assuming it's had enough time to "cool off" (in quotes because that's just what I'm assuming is happening) since the last time the video signal went out/the power button locked.

I probably won't be able to make it to computer store this week, but I'll do that ASAP if I can't figure out what's wrong with it first.
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#4
iammykyl

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Your 500w PSU actually specifies it has only 1 x PCI-E connection. and 2 12v rails run at 18 amps each. so are you using some sort of adapter to get a second connection to the second socket on the GPU, if so, check that is properly seated.


Your new card requires a min 500w PSU with 2 75w PCI-E connectors. I have as yet been unable to find an official number for the amps on the 12v rail, should the PSU prove to be faulty, I recommend you get quality 650w with min 40A on the 12v rail. This would insure you have enough power for any future upgrade.


http://www.newegg.co...9^17-371-059-TS







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#5
quetz32

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Sorry about that, here's the information on the side of the power supply: http://i.imgur.com/LMFDG.png

It has 18A on the 12V rail, which I think should be enough, but maybe I'm overlooking something.

As for the PCI-E connectors, this is what it looks like: http://i.imgur.com/xGnx7.jpg

Maybe I've done something dumb here, I don't know. Maybe those aren't supposed to be used at the same time, and that's my problem. I did always use both connections at once for my old video card, but maybe having two wasn't required for that, just recommended? My old video card's description read: "500 Watt or greater power supply with two 75W 6-pin PCI Express® power connectors recommended"

Thanks so much for the help so far!
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#6
iammykyl

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Maybe I've done something dumb here,


definitely not. It was about the only way you could connect it up. 2 connections to you old card were needed, as with the new one. I have PMd rshaffer61 who kindly replied and thinks we are heading in the right direction with the PSU.

Did you manage to get to the shop?
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#7
quetz32

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Not yet. Sorry, I've been in the middle of finals - my computer picked a bad time to break.

It'll probably be a few days more, but I'll make sure to report back once I've done that and figured out if it's the PSU. Thanks again!
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#8
quetz32

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Alright, sorry for the wait. You were absolutely right - the old power supply was going bad for whatever reason, and I picked up a new one and my computer's working perfectly again. Thanks so much for all the help, and for broadening my perspective on hardware problems - I was almost positive it wasn't the PSU just because all the fans and drives seemed to be working!
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#9
rshaffer61

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Good job iammykyl for catching the root issue.
Quetz32 great job at discovering it was the root issue and for a successful resolution to your issue.
Well done job for both of you. ;) :cool: :ph34r: :thumbsup:
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#10
iammykyl

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rshaffer61Thank you for your input and praise. (Have to get a bigger hat)



****************

the old power supply was going bad for whatever reason




Great that the issue is solved and fortunate to catch the problem before the PSU died as often other parts of the system get zapped.


Good luck.


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