# Bizarre partial system failure

## cheater512

Ok technically this isnt Gentoo related because its affecting my entire computer including the BIOS and Live CDs.

Computer yesterday was running fine before it just slowed down and went very sluggish.

I rebooted it and hit the following problems.

List of symptoms:

* Sometimes there is a speckled pattern on the screen - including BIOS screens

* At native resolution (1680x1050) on the Linux console there are several 1px wide blue stripes close together going from the top to the bottom of the screen just right of center. The space between the lines is about 8px or so and I'd say there is about 20 stripes total.

* At standard computer resolution (no fbsplash) some text gets scrambled. No graphics corruption at all, the wrong letters just come up. This occurs even on a known good LiveCD running memtest. E.g. 'Moving inversions, random pattern' becomes 'SEgvafg afversagfs$ rafdgm pattern'.

The odd thing is this scrambling is consistent between reboots, and doesnt affect anything. My system stats are unscathed its only long strings stored in the binary.

Occurs while booting Linux as well. Doesnt affect the colour of the text.

* X will not start at all. It starts loading, changes the resolution and then stops at a black screen. Hard drive activity stops.

* Memtest picked up some memory errors, but the memory address where they occured is not consistent. The bit that was incorrect however was consistent.

I'm re-running the test today to get more details.

Diagnosis Steps:

* Checked graphics card. Gave it a good clean. Ruled it out when I noticed text being scrambled

* Hard drives (3 in RAID 5) Ruled out because the problems occur in the BIOS and live cds.

* Temperature. Ruled out when left overnight switched off

* Memory (4x2gig) possibly ruled out due to inconsistent results and swapping chips around and leaving only one in didnt change anything.

The odd thing is that most things work fine. I burned a cd perfectly (for memtest) and another computer confirmed that it burnt correctly.

Does anyone have any ideas to narrow the problem down? The computer has been going for nearly a year without problems.

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## eccerr0r

That leaves power supply and motherboard...

power supply issues are terrible to debug without specialized tools, best debug method is to replace.

motherboard issues are pretty much the same (not to mention the DC-DC converters on board which also power supplies in a sense).  Unfortunately it's hard to distinguish which is at fault and swapouts are the easiest debug method.

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## cheater512

Ok some patterns with the memtest results.

I have 8 gig of memory (8191mb).

The errors always appear in memory addresses around 8900mb.

I've ANDed a few of them together and they all have the following bits in common: 1000101011000001000000000000011100

The end 5 bits are interesting. They all match those last 5 bits.

The bad bytes have a dud bit at 0x00080000. It is supposed to be 1 but its a 0.

Thats the only error there is, and after 2:20 minutes there are only 6 of them.

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## cheater512

Lightening the load off the 5v and 12v rails (unplugging 3 hdds) didnt help at all.

I'm thinking motherboard which isnt good news at all.  :Sad: 

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