My R51 reboots randomly

[Hoyt Koepke]

My R51 laptop (1836-B8U) has begun to suddenly reboot once the computer has been running for an hour or two, after which it reboots every couple of minutes. It started happening several months ago when I was running on battery. Thinking my battery was going bad, I used only AC power, and everything worked fine until recently, when it started doing it even with AC power.

Details:
When it happens, it will simply lock up for several seconds and then start the boot sequence. When I'm in windows, the screen usually shows green or red vertical lines before it reboots and occasionally the subsequent bootloader screen (GRUB) is scrambled.

It also seems to happen whenever the computer comes out of standby. It doesn't seem to be associated with anything else (fan coming on, etc.) except that it usually doesn't happen when I'm not doing anything (and yes, my CPU scheme is set to adaptive).


What I've tried: Hoping it was a heat issue, I took it apart and added extra heat conductive paste to the CPU, but it didn't help. Also, limiting the CPU frequency in the BIOS may have an effect but not significantly. I've tried reseating the RAM, but that didn't fix it.

Possible factors: A few weeks before it all started, I dropped my laptop off a short table onto carpet. It hit on the lower left corner and slightly dented the plastic case but didn't seem to do much else. About the same time, I also put in an extra gig of RAM -- (Samsung brand -- fairly cheap). But the memory checks out fine and the problem still happens when I remove it.

I'm thinking it might be a bad voltage regulator chip or something like that. Anyone know what's going wrong before I pay lots of money?

[Puppy]

First, try to remove the extra added RAM module to see whether it will change.

[Hoyt Koepke]

First, try to remove the extra added RAM module to see whether it will change.

I tried that already ("the memory checks out fine and the problem still happens when I remove it") but to be sure I took it out and tried again. It didn't seem to affect the issue.

[vlyne]

The first thing I would try if my R51 ever took a knock would be to reseat all devices and connectors (including harddisk). It looks like you're experiencing problems with the graphics chip which suggests something is broken on the motherboard.
Cheers

[Hoyt Koepke]

Okay, that makes sense. I think what I'll do is disassemble as much as I possibly can (including taking out the system board and inspecting it). Hopefully I'll find some loose connection or point of failure or fix it. Otherwise, it looks like I'll have to buy a new mobo... I'll post what I find.

--H