[bund]

I have Clamshell iBook with a 466Mhz Logicboard. Apple hardware test reports a memory error while there is no RAM in the DIMM1 slot, so the 64MB chip soldered to the logicboard must be faulty.
According to to following information, there must be a way to disable the part of the memory via firmware without desoldering some pins:
Booting Mac OS X
But I didn't get the appropriate information how to manage it.
In one case Apple disabled memory slots with "incompatible" memory via firmware update:
Apple Firmware update - RAM issues

When DIMM0 is disabled, I can put a 512MB module in DIMM1 and go on....

If there is any information about that - Does anyone know which pins of the memory chip have to be desoldered, so that the logicboard regards the DIMM0 as empty ?

Any help is appreciated.

[Eriamjh]

Why not install some RAM in the slot and remove the onboard ram? If you could locate the chip (or chips), you would want to lift either the power or GND pins. Maybe you could find the pinout online?

[bund]

Originally Posted by Eriamjh 

Why not install some RAM in the slot and remove the onboard ram? If you could locate the chip (or chips), you would want to lift either the power or GND pins. Maybe you could find the pinout online?

Yes, this was my second thought. I believe that onboard memory is a bank of 4 chips (i located it on a defective 300MHZ logicboard) but there are no pin numbers written down.

My hope was that there would be an easier way - before i try to rip some pins or the whole ram bank off the logicboard.......

[omgwtf]

if the onboard's 66-pin tsop, pins 1, 18, and 33 should kill power for the chip. on an ibook, killing one chip kills the entire bank. don't know how it is on a clamshell, but possibly the same. should be either the first or fourth chip in the series (depends on how you look at the ibook mobo).
see http://forums.macosxhints.com/showpost.php?p=333016&postcount=12