[idykenano]

I have a G5 Powermac full of kernel panics and job crashes (its used mainly as a workstation for computational chemistry). A lot of the jobs return memory errors, so I ran memtest.
The memory in this machine is 2x 1gb, straight from Apple I believe.

This is a sample of the failure ridden memtest log file:

Mac OS X 10.4.11 (8S165) running in multiuser mode
Memory Page Size: 4096
System has 4 PPC processors(s) with Altivec
Requested memory: 1748MB (1833750528 bytes)
Available memory: 1748MB (1833750528 bytes)
Allocated memory: 1748MB (1833750528 bytes) at local address 0x0000000004008000
Attempting memory lock... locked successfully
Splitting allocated memory into 2 comparison buffers...
Buffer A: 874MB (916875264 bytes) starts at local address 0x0000000004008000
Buffer B: 874MB (916875264 bytes) starts at local address 0x000000003aa6e800

Running 3 test sequences... (CTRL-C to quit)

Test sequence 1 of 3:

Running tests on entire 1748MB region...
Stuck Address : ok
Linear PRN : ok
Running comparison tests using 874MB buffers...
Random Value : ok
Compare XOR : ok
Compare SUB : ok
Compare MUL : ok
Compare DIV : ok
Compare OR : ok
Compare AND : ok
Sequential Increment: ok
Solid Bits : ok
Block Sequential :

FAILURE! Data mismatch at local BUFA address 0x000000000d9e2468, BUFB address 0x0000000044448c68
BUFA Data: 0x0100010101010101, BUFB Data: 0x0101010101010101

Checkerboard :

FAILURE! Data mismatch at local BUFA address 0x000000000d9e2058, BUFB address 0x0000000044448858
BUFA Data: 0x5545555555555555, BUFB Data: 0x5555555555555555

Am I right to decipher that my ram is bad? It seems like a read/write problem with the ram, which I'm hoping is in the ram and not the logic board. Any experience with memtest?

[Dork.]

Try removing one RAM stick and then running the memtest, then run it with only the other stick. If you want to be excessive, try each RAM stick individually in all the slots.

If the failure seems to follow the RAM stick around, then the RAM stick is at fault.

[idykenano]

G5's only run in matched pairs. This is all the memory I have, so I can't remove just one stick and try the memtest again.

I have however thought of another thing: I need to move both dimms to another slot (ie slot b instead of a) and try again to make sure its not the ram socket.
I'll post back when I try that.

[idykenano]

Just kidding. The G5 won't power up with the memory sticks in spot b instead of a, I guess the memory not only has to be paired but ordered.

[Dork.]

Try swapping the memory in the slots, then. I think that if the flaw is in the RAM, the memory address of the flaw ought to change....

IMHO, if it's a single flaw, that's probably an indication that the problem is in the RAM stick also. A motherboard issue would likely result in a bunch of failures.