Power on and off

[Tel]

Like others on this forum, I've had problems with first boot. My system is exactly as described on the mysuperpc website. On the first boot, when I press the power button, fans run and led's light, but everything turns off in about two seconds, comes back on, and the cycle continues.

No change with a single memory stick and no video card. I've triple checked all the connections, and I've even taken the mobo out and tried to run it on a wooden table to be sure nothing was grounded. No change.

Any clues as to where to look? If I have to return something, I can't tell if it's the PSU, the mobo, or the CPU cooler. Any insight would be greatly appreciated!

Thanks!

[Tel]

I've been going over posts with similar problems. Seems like a common problem is forgetting to connect the 4 pin CPU plug. My mobo is a gigabyte p55 ud4 and it has an 8 pin adapter. The power supply has 2 4 pin plugs that fit, so I used those. However, the shape of the actual pins on one of the plugs doesn't exactly match the mobo, but it seem to fit fine.

Might the problem lie there?

[RickyTick]

I've been going over posts with similar problems. Seems like a common problem is forgetting to connect the 4 pin CPU plug. My mobo is a gigabyte p55 ud4 and it has an 8 pin adapter. The power supply has 2 4 pin plugs that fit, so I used those. However, the shape of the actual pins on one of the plugs doesn't exactly match the mobo, but it seem to fit fine.

Might the problem lie there?

Good possibility.

That motherboard does not have onboard video, so you'll probably need the video card.

[Tel]

Actually, the problem persists with or without the video card installed. The video card has its own power adapters, and when the video card is installed, its fan happily starts up when the power button is pressed, but immediately shuts down when the rest of the power cycles.

Basically, all the fans come on (power supply, case fan, CPU fan, video card fan), the board LED's light, but just for a second, then it powers down. A few moments later, the process keeps repeating itself.

I'm about to reseat the CPU and apply new thermal compound, but I don't have high hopes.

[vx91]

Tel - I have the same issue going on. Same question about the 12V connectors also. One connector has perfect match, the other fits, but not everything matches.

Curious what you find out.

vx91

[zburns]

Several comments. Many assembly problems have a simple and obvious solution. The solution lies in isolating the problem to one component.

The fact that your power supply cycles on and off probably indicates a short or partial short circuit causing the overload protect circuit in the PSU to trip in. There could be other more sophiscated reasons that the PSU is shutting down but you would have to ask the PSU manufacturer that question. I assume your CPU fan is running all the time.

You have an 8 pin connector on the mobo for the CPU power supply "mating" connector. If your 8 pin psu plug is composed of two 4 pin plugs, then one of the two plugs will go into the top half of the mobo 8 pin connector and the other plug will go into the lower half of the mobo 8 pin connector. Under no circumstances should you be able to reverse this, with the bottom plug going into the top and vice versa.

Your user manual clearly shows the position and shape of each pin that plugs into the mobo.

Your "not matching" comments should apply only to a "rounded" plastic pin easily going into a square hole on the 8 pin mobo plug. Everything is ok as long as one 4 pin plug will only go into the top and the other "only will go into the bottom". The two plugs will not be interchangable. The plugs should "insert" easy and smoothly.

Also, leave out your video card. Disconnect the PSU power connectors to the external drives, the HD, the DVD drive. If you still have the problem, then remove all cables to the mobo except the "mobo" 20 or 24 pin large connector, the 8 pin power connector and the case front panel wiring.

If you still have the problem at this point, you might try removing all front panel wiring except the wiring from the power switch.

At this point you would then have the mobo and the front panel power switch only hooked to the psu. This isolates your problem to the PSU or the mobo or the CPU. Make sure your CPU fan is always operating.

I have called Gigabyte USA customer service (Ca) several times and each time felt like I was talking to a competent person.

One further comment. Normally when I write something on a gigabyte mobo, I have had the advantage of being able to look at the actual User Manual from gigabyte direct from the web. This time I was unable to access the manual, hence I am working from memory; but the one thing that has impressed me with Gigabyte is the quality of their manuals.

[vx91]

Thanks Z-

I actually did all these things. The only other suggestion I saw was to try and boot the mobo outside the case . . . . but I figured I could not connect the power switch and it would most likly not work.

The LEDs on the Mobo seemed to all 6 be lit up indicating a power surge.

You are spot on regarding the 8-pin connector.

So I am exchanging the mobo and cpu and will try again.

vx91

[zburns]

Is you mobo part # just the plain description "p55 ud4" or is there any suffix after the p55 or the ud4. I am able to download the manuals. I looked at the p55 ud4 manual and found only 4 phase led lights in the upper right corner of the manual mobo diagram.

You say you have six lights; how many are grouped together and roughly where are they on the mobo?

Also, you have to consider the possiblility that the psu is faultly; unlikely, but possible.

Did you use a static control wrist strap during the build. Static is worse in dry, cold climates; this is the time of year to start looking out for it as weather gets colder and dryer. Theoretically, static could be a "greater problem" on the very small nanometer newer (32nm) quad processors than the older dual core 90 nanometer. The spacing between transistors and other components are much closer in the quads.