Homebuilt computer help needed

Strange things are afoot with my computer. Here’s the deal. I went on vacation, came back, and my computer was acting all weird: it would POST but fail to load the OS, sometimes fail to POST, bunch of weird stuff. The mobo, an Epox EP-9NPAJ, gave an error code, which, according to the support site, was Very Bad.

That’s odd, I thought, I wonder what happened over my vacation, but hey, I’ll just get a new motherboard. I buy an Asus A8n SLI Premium. I hook it all up, the onboard power LED lights up, press the power button, but nothing happens. Fans don’t spin or nothing. I take it out of the chassis, leave only the video card, one DIMM, and the processor, hook the power up, and do the little thing in which I touch a paper clip to the two prongs that attach to the power button, and everything works fine.

I turn it off and try again. I keep touching the prongs, but nothing immediately happens… after a minute or two of fiddling, it turns on again.

I return the mobo to the chassis, try again by connecting the power button, it doesn’t work-- power LED on, but fans won’t spin, won’t POST. Again with the paperclip, it takes a little fiddling, but it starts once. Hm… maybe a bad power switch? I try the paperclip again, fiddle around, bu it just won’t go again.

I’m extremely puzzled here. Can anyone suggest what might be wrong here? Could this be a power supply problem? (It is an Antex 400W that is just about a year old… seems kinda soon for a failure?)

I would try a different power supply. You may have a bad pin or two in the supply’s MB connector even. I’ve had power supplies that needed replacement, because the connectors became undependable.

Was your computer plugged in while you were away? Maybe a power surge after an outage?
Anyway, I had a similar problem with my power supply. The first time it happened, I could hear it trying and then fizzing. When I hit the power button again, it would make more noise and then shut down. I kept pressing with no luck and finally gave up and walked away. Awhile later I walked into the room and the damned thing was on - fully operational. I apparently had left the switch in the “on” state and eventually the power supply decided to work. Ran fine once I got it going, but just couldn’t count on getting it going. One time it came back to life after about 6 hours of being not quite dead yet. I decided I’d tempted fate long enough, replaced the power supply and all has been well since.

Yes, my computer was plugged in while I was away.

Is there any simple test I can do to see if the power supply is the problem without going out and dropping $100 on a replacement that I may or may not need?

Are there any other potential culprits here, besides the power supply or a bad pin or two on the motherboard?

I actually had the same exact thing happen to me…

Turns out I put in an extra motherboard standoff, and it was creating a short :smack: . Thankfully, the motherboard could detect the short and just wouldn’t power up, so there was no permanent damage. I’d check something like this first… make sure there aren’t any extra standoffs or odd bits of metal floating around.

If it’s just a loose connection on the power supply, that can be fixed with some careful fiddling. Just squeeze any loose connectors that you can identify, so they’ll make a better connection to the pins on the motherboard.

Other than that, it sounds like a power supply issue. It’s a bit surprising, considering you have a quality brand that isn’t very old, but even the best parts break. You shouldn’t have to pay $100 though, since you can get another Antec replacement from somewhere like CompUSA for $60ish, or less if you’re not in a hurry and can order it online. Plus, you’ll have a backup if the problem turns out to be something else.

I’d be suspecting a short in the PSU or along the molex connectors for either the motherboard or +12V line(s). The intermittency of function when you short the power posts and the fact that this happens with two distinct motherboards suggests that either the PSU isn’t getting the power-up message, or isn’t successfully sending the power back to the motherboard and components. Antec isn’t cheap so I’d be a little surprised by it dying after only a year, but it does happen.

This is assuming that all other considerations have been looked after – specifically that the motherboard is properly isolated form the case by risers. (Unlikely novice mistake I realize, but geriatric moments happen. I bought the same motherboard a year ago and I spent over an hour trying to figure out why it would power but not POST before realizing I forgot to connect the +12V. :smack: )

Could be two unrelated problems - old Epox board dies for whatever reason and then there’s something funky on the new Asus.

First thought was a short with a spacer like another poster mentioned. Something else I’ve seen (done) that can cause the machine to simply not power up at all is to accidentally move the “CMOS reset” jumper into place. Take the manual and double-check the position of all those dang little jumpers and make sure that none of them are in the wrong position (in my case it was an Abit mobo that had a diagram upside down so I thought I was putting a jumper where it needed to be).

I’ll check the spacers, too. I don’t think I really looked that carefully at them.

When the board was out of the chassis, and I tried shorting the power-on posts, one time it worked pretty quickly, the other time it took a minute to do it. That seemed odd. Normally if you short the posts on a well-functioning computer, it should just spring to life, right?

I’m going to toss one more suggestion onto the pile, Ravenman. Check the switches on the front panel of your case. I built a PC that had almost the exact same symptoms as yours. I had some spare parts on hand and spent a lot of time swapping stuff out before I finally figured out that the reset button had a loose connection that kept shorting out to the chassis (all-aluminum case with no plastic mounting areas.)

Try pulling the case connectors off of the motherboard pins and metering them out for shorts. It’ll only take a couple of minutes, but could save you some aggravation.

Well, I read all your replies carefully, bought a nice new power supply at Compusa (too impatient for Newegg) installed it… and victory! Everything appears to be working great. I appreciate all your help.

Try Happ controls, they are economical, ship anywhere, any way, and very reliable. Also they feature humans on the phone lines who actually are familiar with the products they are selling (ie, they can answer questions)…

Link: http://www.happcontrols.com/

you should get away for under half that cost $50-60, depending on how you have it shipped…

regards

FML

$100 nothin’. The Thermaltake PurePower 500W I bought last year set me back $160 (Canadian). It’s modular though, so I only need to plug in the molex connectors that I’m actually going to use which eliminates a bunch of snakey, unused connectors hanging loose all over the place.

Glad to hear of your success. Shame a good Antec PSU went that quickly, though, but you sometimes get lemons even in the higher end stuff.

Have fun with you new A8n. I have that same motherboard in my second workstation and love it.

I like being able to hook 8 hard drives to it. :smiley:

Good. Your welcome.