PC won't start

Not quite sure if this is the right place to post as I'm not sure what the problem is. Googled it, and found no useful answers.

Okay, I received a new computer case and I have now put everything from my old PC into the new case. My PC worked fine before, but now it won't even POST, at least it won't show it on the screen. It powers fine, I get the sound and the light and stuff, and I'm fairly sure I haven't damaged any hardware or connected something wrong, even though this is actually the first time I've built the PC myself. There's also light in the graphics card, so that's not the problem. Neither is there dust in there or the wire from the PSU is used to anything else than the graphics card. It is an Asus EN9800GX2. It's basicly an NVIDIA XFX GeForce 9800GX2 with some Asus stuff in it. So, what could the problem be? My screen comes with the message "No signal detected" when I start it. What's weird is that when I plug in the wire to the computer my screen doesn't react, usually it lights up before it gives the no signal detected message again if the computer is in standby mode or something like that.

Ask if you need any additional information.

EDIT: Also, my keyboard (Logitech G15, with a little LCD screen) doesn't light up, neither do my mouse (Logitech G5)

 

Unless you've fried something, which is more serious, you may want to try this:

Sometimes the PCI bus can latch an address line. This effectively prevents a full POST and items like the USB / RAID / PCI-E won't process.

When I see this situation, I unplug the USB devices, and turn off the video devices. You don't have to unplug the video cable, just switch it off. This stops any spurious communication.

Then I unplug the computer from the wall plug. This I leave off for about 5 minutes while I dig around in the shop looking for a legacy keyboard. Although it isn't always necessary, I like to have one on hand.

After 5 minutes, I plug the computer back in, and power it up. I don't turn on the video screen yet. Instead, I wait for the LEDs to flash on the legacy keyboard. This usually indicates that the address line has unlatched. You can now turn on your video screen.
Of course, you can also plug in your USB keyboard, if you like. I usually wait until Windows boots, then I plug in the USB keyboard. Leaving the legacy keyboard attached won't interfere with anything, but this you can remove on you next shutdown.

 

Check to make sure everything got plugged back in as well, particularly the 4-pronged 12V CPU power. It's an easy thing to forget. Fans will spin, drives will spin up, everything looks normal, except you won't get any POST beep or video. If you're getting a POST beep, that's not it, check to make sure everything's seated.

 

No "beeps?" ... I had a succession of beeps, (4 then 2,3?) on a Dell--I forget now, but with the same problem you are talking about, it turned out to be I had knocked loose one of the ram clips, and it had gotten loose....didn't *seem* like that was the problem, but I kind of jiggled'em a little bit, and then it booted up fine...and up 'til then I kept changing everything out, and it wouldn't post, just the 'beeps...'which if it you *do* get them, you can google'em, find out what they mean...or better, post'em here, somebody wiser'n me will know...

Anyway, sounds like something you'll find, usually simpler than it appears, at first...best wishes...

 

Ok, assuming a legacy keyboard is one of those old keyboards connected by a purple round non-USB thingys, it did not work. What happened with the computer before was that it started with the fans at the highest speed. Then after a few seconds it reduced the speed and started POST on the screen. What happens now is that it won't go out of the high fan speed-state. It has happened before, but that was because my graphics card is SLI and I had plugged the cable in port number 2. Are there any symptomphs that I've fried something?

 

No beeps, and the RAM seems to be inserted right. No movement when I touch them. I can't seem to find my CPU, since I didn't build the PC (lol). I'll look for it in the mess of cables.

 

Did the legacy keyboard flash it's LEDs? If it didn't your box is still stuck. Since you have an SLI mobo, I'd unplug the power cord, and swap the video card into the second SLI slot. Chances are good that re-seating the board in another slot might unlatch the address bus. Also, take a good look at the power connections to your video card. Occasionally the molex pins can get spread, or pushed back, just enough to be annoying.

 

Yeah, no beeps, then I think I'd be looking closer at what prometheos and Bluepickle suggested, going over all my electrical plugins; I've kind of been doing the same thing lately, changing motherboards around, building computers back and forth, and it's always something basic, like power supply, but he's right, I'd be unplugging everything wasn't vital, including chassis fans and such, anything, it always surafces eventually...frustrating tho, I have a little post checker thing, that I can plug into a pci slot, and it will tell me, but's a pain to use and decypher, as it has comes w/pamphlet in computer translation of Chinese, which is supposed to be english :-D

...I'd be doing just what I'm sure you've been doing: unplugging everything, going over every silly plug in, from 'start button' wires to pci card, and again, best wishes, until someone comes along who might have better knowledge of startup stuff, cause when you can't even get to bios/cmos, it's a pain....and trial and error, and swapping stuff out, is all I know...

 

Haha, figured out the problem. No power to the CPU. Now, I only need to find the right power plug from the power supply. Thanks for the help all, I'll post again if there's any additional problems.

 

It should be a square plug with two yellow wires, and two black ones.

 

Awesome, it worked! Posting this from my computer, thanks again! Feels quite good when you built your own PC for the first time and its actually working (with some help).

 

I just built my first one a few months ago too: it's a really good feeling when it finally works...and makes me much more comfortable working w/hardware now. I'm kind of studying for the A+ exam, and learned way more doing that, than I ever did working on the ones down in the class here...and of course, on here...unfortunately, now I've built three, and think I know what I'm doing, and am always chiming in on here w/advice and stuff :-D