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New build keeps restarting after 2-3 seconds

  • Homebuilt
  • Systems
Last response: in Systems
November 10, 2010 6:29:57 AM


I've recently purchased and built my own PC, my first time doing so.

All the parts are brand new except for the power supply, which is about 3 months old.

CPU: Intel Core i5-760 Lynnfield 2.8GHz LGA 1156 95W
Motherboard: ASRock P55 Extreme LGA 1156
RAM: G.SKILL ECO Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800)
Video Card: SAPPHIRE 100315L Radeon HD 6850 1GB 256-bit
PSU: OCZ ModXStream Pro OCZ500MXSP 500W

Hardware wise, I think everything should be compatible.

Heres the catch, after finally building it, I power on. It starts up, all the fans start spinning, but after 3 seconds, the system reboots itself this cycle continues indefinitely. I don't know what could be wrong, something I did or maybe defective parts? Possibly a case of inadequate power supply?

I'm hoping someone can shed some light on this issue for me, because it's quite frustrating.

Thank you all

More about : build restarting seconds

a b B Homebuilt system
November 10, 2010 8:00:38 AM

Try with one stick of RAM at a time. Try with some other PSU.
November 10, 2010 10:51:18 AM

Or try see how your bios is set up with regards to hard drives and dvdwriter, it may not be detecting a sata connection
Related resources
November 10, 2010 12:52:39 PM

Hi iammzz,

I had a simular issue with my 11 month old home build, on first boot up of the day
it would either go into the power on/power off cycle or the GPU fan would be spinning at 100% and the system would not post!

Changed the PSU after advice from another forum member and that cured it.
After testing the RAM perhaps you could try anther PSU.

Good luck and regards keith263
November 10, 2010 8:46:52 PM

I tried with 1 stick of RAM, same issue.

So now it comes down to the PSU?

I thought a PSU like this would be good enough to handle my not-too-extreme system, could it be faulty?

Or maybe I missed something, I did make sure to attach the 8-pin 12V ATX and the 24-pin main connector, and attached the cpu-fan. Could it be something else I forgot?
a c 122 B Homebuilt system
November 10, 2010 9:10:17 PM

OCZ PSU's are, at best, extremely mediocre.

Work through our standard checklist and troubleshooting thread:
I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

If not, continue.

I have tested the following beeps patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different.

Breadboard - that will help isolate any kind of case problem you might have.

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU. You do have a case speaker installed, right? If not, you really, really need one. If your case or motherboard didn't come with a system speaker, you can buy one here:

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU.

Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card. Silence or long single beeps indicate a problem with the memory.

Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.

Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.