No power to monitor, keyboard and mouse.

HaouaHaoua
edited April 2012 in Hardware
Hey guys, I'm new to this forum but I've seen some of the other discussions and was wondering if I could get some help with a problem I've been having. I was live streaming Eve Online the other day when my comp froze up completely. I powered it down with the power button and it shut down normally. However, I went to start it up and it powered up normally (fans started, Alienware LED lights went on for the first restart but not afterwards, etc) except the monitors (2 of them, both on the same video card) didn't acknowledge that the computer was on. The keyboard and mouse didn't light up at all (both are USB). So the computer runs as it should at startup, just the peripherals aren't receiving power. When I unplug the keyboard/mouse and start to plug them in, they light up for a split second, but not after they're plugged all the way in.

I've tried many things. The simplest being switching out the keyboard, mouse, and monitor with others. No luck there. I've unplugged the power cord, drained the power by holding down the power button, and leaving it sit for a while. I've tried reseating the RAM, graphics card, and hard drive. I haven't tried replacing the CMOS battery. I tried starting the comp with no RAM, and the motherboard did produce the RAM error beeps so the motherboard seems to work. Theres a small light on the front of my comp that shows when the hard drive is in use, and it does light up. So HD seems to be working.

Specs:
Alienware Aurora R2
Intel® Core™ i7-860
6GB DDR3-1333 SDRAM
1TB 7,200RPM Hard Drive
24x CD/DVD±RW Burner with Double Layer Write Capability
ATI Radeon™ HD 5870
10/100/1000 Network
Microsoft Windows 7 Home Premium (64-bit)

Comments

  • Straight_ManStraight_Man Geeky, in my own way Naples, FL Icrontian
    Can you tell us how big the power supply is??? Could be a damaged power supply with power to video card voltages and USB power voltage out. PSU damage can occur two ways-- minimally overload for a longer time yields delayed damage, way overload and and damage happens quicker. I would have PSU checked lout first thing.

    Best of luck and let us know how it goes, ie what happens with the PSU test.

    John.
  • HaouaHaoua
    Thanks for the quick response. The actual size I'm not sure of, but it's 875W PSU. And it's a mid-tower case. I'm new to the internals of a computer. All of the fans and such are running fine, so could the PSU be damaged and effect just the monitor and USB? I'd think it would effect everything but I'm not sure.
  • Straight_ManStraight_Man Geeky, in my own way Naples, FL Icrontian
    Ok, modern PSUs put out multiple voltages along sets of wires called legs for tech term. Internally, they typically generate 12 V first, then step it down to 3 and 5 volts each, and further for a tiny output leg, put out 1.5 volts.

    Surges can damage the lower voltage circuits in a power supply easily, surges smaller than what would cause the power supply to completely fail. USB and video cards on PCI-e busses (like your video card), run power on 3.3 and 5 volts to video and on 3.3 volrs to USB to power things like mice and keyboards. this routed to motherboard first, then circuitry (internal to motherboard and also in form of things like capacitors that essentially function as something functioning like mini rechargeable batteries which are on motherboard and look somewhat like plastic coated tiny cans) whic then is routed to power pins in video and USB sockets. No power to video card, no video. No power to USB, nothing USB works. Could be motherboard AND power supply, but power supplies are designed these days to protect by failing first.

    Therefore, voltages from PSU should be checked first. that is a tech's job to do it right.

    What ,makes me think this?? First, sudden failure-- possible, no make the PROBABLE surge. Sudden damage of some sort in any case. Second, USB circuits TRY to feed power as indicated by lights flashing on on keyboard and mouse, then cutting to off. USB power circuit is not being given enough power to power a keyboard and mouse, or that power circuit is damaged on motherboard, or both, for even a short time.

    PSUs are designed these days to intercept some surges, and real big ones will cause PSU fuse to blow inside of PSU. Takes a tech to fix that, and then troubleshoot PSU to make sure it is undamaged.
  • HaouaHaoua
    I've been thinking of taking it to geek squad (best buy) and having them take a look at it. I know they do a quick test with a machine to pinpoint the problem or possible cause. I'll give them the info to see if they can do something to fix it, and hopefully it'll just be the PSU and not the MoBo as well. Thanks for the info, I'll post any other information they give me.
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