It seems video memory on my Thinkpad A31p is broken.

First I thought it was due to xorg drivers, but then I saw the same kind of corruption in BIOS. An upgrade to the latest BIOS version, which mentions a fix for video corruption, didn’t help either. Nor a downgrade - I actually had the latest already, and I believe I installed it around when the problem appeared the first time.

Since I had to boot windows for the BIOS upgrades, I can also tell that the same problem occurs in Windows (and in BIOS, actually, but less often due to the much lower resolution). And I’ve found out, that it gets better when I slightly hit the back of my laptop… but only for a short time - until I put it back on the desk.

From what I can tell - and I can take screenshots of the corruption - it is faulty wiring to the video memory. From my naive point of view, one of the two video memory banks my system seems to have has a broken wire.

As you can see from the photograph or the screenshot below, there is a checkerboard pattern on my screen, with the highmost blue bit set in every 4th pixel column in every odd square of the checkerboard.

This makes for some really great effects: If you have an image which has a gradient, the effect will disappear for the lighter parts:

My explanaition is that when writing to the video memory, in one bank there is a varying chance of this one bit becoming set, causing the blue stripes. The other video memory bank is fine, so no corruption there (unless copied over from the other memory bank)

I opened an “Electronic Service Call” with IBM, and I have to say that their service rocks. I got a callback within a few minutes. The caller verified my model and serial number, told me that my 3-year warranty extends until August (I bought the machine used, I have it for 1.5 years now) then transferred me to technical support. Technical support quickly asked me if I can see the same corruption in bios - yes I can: some red dots sometimes appear there on the IBM splash screen - and then told me that I’ll have to send the machine in. They’ll be shipping me a box to send it in now.

Now if they manage to get me a replacement within a few days I’ll be really happy… ;-) Wish me good luck.

The big drawbacks are:

  • I won’t have my usual work environment for a couple of days soon
  • If I get the whole unit replaced, I would lose the really cool Debian Logo I put on the back of the display. I think I still have a smaller rub-on squirl left from LinuxTag ‘02, but the big one looked so cool… If only I could remember who made these nice stickers and gave it to DDs on LinuxTag ‘02… ;-) Well, maybe they just disassemble it and replace only the video board.

Here’s a shot of that great sticker:

It’s not a flat sticker, but a rub-on of the actual squirl and letters - with nothing inbetween. The “Debian” text is only visible by its smooth, reflective texture in contrast to the rough black background typical for IBM Thinkpads. The red of the squirl has an excellent color, making it stick out very prominently. I love this sticker - it makes my machine so unique. ;-)

A plus of the replacement is that probably my backlight will be fixed, too. When I reduce brightness it gets a reddish tint at the edges, which goes away after five seconds of full brightness.

Even with this being my second defect of the notebook, I can recommend IBM a lot. (The first defect was the DVD writer, which is used by lots of other companies, too. I don’t blame IBM for that) - their products work very fine, and the service is great.