New build problem - reboot loop

[DDave]

Hi,

I'm hoping someone here can help suggest a fix for a continuous system-rebooting problem I have with my new brand new build.

Spec…

Antec Sonata III Piano Black Quiet Mid Tower Case - With 500W EarthWatts PSU
Intel Core i5 750 2.66GHz Socket LGA1156 8MB L3 Cache CPU with stock HSF
Gigabyte GA-P55-UD3R iP55 Socket 1156 8 channel audio ATX Motherboard
Crucial 4GB (2x2GB) DDR3 1333MHz/PC3-10600 Memory Kit CL9 1.5V
MSI HD 4850 OC 512MB GDDR3 Dual DVI Out PCI-E Graphics Card
Samsung SpinPoint 1TB Hard Drive SATAII 7200rpm 32MB

A bit of history…

The original build went smoothly – except – the system bios would not recognize RAM in the second dual channel slot (slot DDR3-3). It worked ok using one slot (DDR3_1) alone or using both single channel slots (Slots DDR3_1 & DDR3_2). I then had the Crucial RAM kit replaced but this made no difference. I also tried using another brand of memory, but again the problem persisted.

I guessed this must be motherboard fault so RMA’d both the motherboard and RAM kit for a direct swap.

The current problem….

After rebuilding with new RAM and motherboard the system now repeatedly begins to power up for about 3 seconds (all fans spinning normally), then turn itself off for 3 secs, then re-boot again for about 3 secs before shutdown again for 3 sec…. and so on...until you hit the main AC switch. There are no bios beep codes.

Based on suggestion from other posts here, I’ve so far tried: reseating both RAM sticks, HSF and CPU, attempting to boot with either single RAM stick (it’ll give continuous beeps if I try to boot with no RAM installed), removing/unplugging everything (graphics card, HDD, DVD drive, USB and audio connections, front panel connections) except for CPU/HSF, RAM, PC speaker and power supplies (24 and 8 pin ATX) and removing the board from the case and placing it on top of cardboard (in case the PCB was shorting on something). On firing the system up by shorting-out the power switch pins on the motherboard the system still continues to re-boot every few seconds.

I’m now guessing this is most likely (another?) faulty motherboard, if not perhaps RAM. The CPU and PSU worked in the first build so I’m thinking these are less likely.

Any ideas or advice would be appreciated. Thanks.

[michael_d]

If the computer reboots on its own my first suspect would have been the PSU unless it had worked properly with another Motherboard/RAM. But if I understand you correctly you did not have this problem until you replaced both the motherboard and RAM, so it leads me to believe it could be the motherboard and/or RAM or combination of both. Unfortunately the only way to find the cause of the problem is by trial and error and involves swapping motherboard/RAM.

I had a similar problem my computer would randomly reboot but it was due to virus infestation once I cleaned it up, no more reboot problems.

[DDave]

If the computer reboots on its own my first suspect would have been the PSU unless it had worked properly with another Motherboard/RAM. But if I understand you correctly you did not have this problem until you replaced both the motherboard and RAM, so it leads me to believe it could be the motherboard and/or RAM or combination of both. Unfortunately the only way to find the cause of the problem is by trial and error and involves swapping motherboard/RAM.

Thanks for the reply. Yes, this PSU did boot the system normally using the previous motherboard and RAM, although it wouldn't detect memory sticks in slot 3. I'll try to borrow some other DDR3 RAM for testing.