Requesting Advice re: Random Reboots

[pearle]

Before I explain the problem here are the specs (this is not a new build though some parts are newer than others -- it has been running stable since Dec 2008):

i7 920 @ stock speed
Asus P6T Deluxe w/ latest Bios (as of a couple of days ago/after the problems began)
3 2GB Corsair Dominator 1600 sticks
Corsair AX-850 (less than 2 months old -- replaced failed Enermax)
Corsair HE-50 water cooler
ATI/Sapphire 5870
2 300GB Velociraptors in RAID 0
3 other WD drives
Sony optical drive
Soundblaster Audigy 2 (yeah, ancient -- not the problem though)

This weekend my computer started randomly rebooting. This happens both while the computer is essentially idling and when it's under load. It also likes to reboot while rebooting -- in fact, it seems addicted to it. Sometimes it doesn't even post before it power cycles again. Other times it will reboot during post, during windows boot, at the log in screen, or at the desktop while I'm simply surfing the web or even when I'm doing nothing but looking at the monitor (I'm not THAT ugly). It will reboot both when practically idle or when under heavier load while gaming.

Once the computer reboots it seems to go into a reboot cycle where it will reboot again very shortly. As I mentioned above, sometimes this happens very quickly (a second or two) or sometimes it will last 5 or more minutes and I'm able to log into Windows and dick around for a bit.

I've removed or swapped many of my components. I've eliminated all hard drives, the optical drive, GPU (swapped an 5870 for a GTX 280), and sound card as being the problem. I have successfully hooked my PSU up to another rig (a Core 2 duo rig) and it ran fine for 22 hours until I finally turned it off to do more testing with my i7 rig. The PSU in my other rig doesn't have all the appropriate connectors to hook up to my i7 rig (not enough PCI-E power adapters for the video card) so I have not tried that. [Edit: I have since managed to get my older PSU working with my i7 and it still reboots randomly so it's not the PSU]

I also reflashed my motherboard bios to see if that helped. It did but only for a while. The computer ran fine for almost a day before the reboot hell started all over again.

I have not eliminated memory yet as I would have to buy more to swap in. I have run memtest 86 from a CD several times (all hard drives disconnected) and the computer will last anywhere from 2 to 15 minutes (usually reboots inside of 10).

I am leaning towards the motherboard being the problem but I am far from sure at this point. How likely is it that the CPU is the problem? Would bad memory exhibit these symptons? From my perspective, it seems to be more likely to be power related.

Temperatures are all fine. The CPU idles in the mid to high 30s (celcius) and will hit the mid 60s when fully loaded with Prime95.

I even went out and bought a voltage regulating APC UPS to see if my power might be a problem (I live in an apartment). The UPS shows voltage at a stable 119 to 122 volts.

Any ideas or suggestions? Perhaps someone has encountered similar behavior. My next step may be to buy more memory so I can eliminate that as the problem -- having more memory will not hurt though it's a bit of a waste money wise. The motherboard and PSU are both still under warranty.

Thanks to anyone who has advice or suggestions.

 

[djstarfox]

Change your memory speed to 1066MHz and re-test. Make sure mem voltage is between 1.5V and 1.65V in BIOS.

 

[pearle]

Tried 1066 w/ 1.64 (bios doesn't let me enter 1.65) but no luck. In fact, the computer resets now before the monitor even turns on.

 

[Almighty ODST]

I had the same sorts of issues with my i7 920 build but my motherboard is EVGA. I replaced my PSU (750tx -> 750hx) and it happened once more after replacing the PSU. I bumped the voltage up on the processor a bit and that fixed my problem. It's more than likely not the same, but maybe give it a shot?

 

[pearle]

Do you remember what setting you used for the CPU voltage?

 

[pearle]

I'm testing with 1.35V for CPU, 1.64V with RAM @ 1066Mhz.

I also managed to get my older 550 Enermax PSU working with using an old Geforce card but It still randomly reboots. So I guess that leaves Motherboard or RAM.

 

[Crispy002]

If you can boot into windows try looking for logs that might provide a hint, vista and 7's logs can be found in the action center. I don't remember where XP keeps them

You can also try narrowing down the RAM somewhat by trying only 1 stick at a time in the appropriate slot of your mobo. To eliminate it further, if you live near a store that allows RAM to be returned, you can always pick up a set for testing and return it a few days later. Read the fine print to avoid restocking fees and such though!

 

[pearle]

Thanks for the advice -- I was under the impression that with triple channel memory I need to have all 3 sticks installed? Is it true I can install 1 stick at a time with an i7 x58 setup?

BTW -- I checked the windows event logs early on when this first started happening and couldn't find anything other than 'Windows shut down unexpectedly' type errors. Unfortunately, at this point I'm not sure the computer will stay on long enough to log in and peruse the logs again.

Edit: Testing each stick individually now.

 

[pearle]

Each memory module passed memtest when tested in isolation (only one slot filled) so I guess it's time to call up Asus and request a RMA.

I reseated the memory yesterday so I doubt that was the problem.

 

[djstarfox]

Yeah, sounds like memory or the memory controller (more likely). Make sure you tell them the problem happens with more than 1 memory stick installed; I've read posts here about some RMA people only testing with 1 stick and then returning the board as is.