|Well all the 1GB sticks are identical and marked "PC133 128Mx64 UNB Non-ECC SDRAM". One turned out to be bad however. But I don't think that is the end of the story. I had also installed 2.5GB of known good working RAM and it still would not boot.|
The defective RAM was identified as follows. POST would count up to the 3G, but the machine would reboot and show progressively less memory after a couple times down to just 2GB. The machine never did boot with all three 1G sticks installed. And to clarify things before my confusion becomes yours, the defective stick was only ever installed in slot 0.
Assuming that the problem would be in slot 3 due to the MB documentation (see riiders post #1) I pulled the RAM from its slot. POST would count up to 2GB, but the machine would still not boot. At that point, I noticed mechanical damage on the surface of two of its IC's. That made it only suspect to me, so I reinstalled it. After reinstalling it, the machine stopped showing anything on the monitor. It was then that I realized it was not the slot 3 RAM I had just pulled out and stuck back in but the slot 0 RAM. I had been looking at it backwards and only realized it when the monitor stopped showing anything. POST didn't seem to care as much as I thought it would because it had reported on the RAM even with no stick in slot 0. Does that seem odd to anyone else?
Anyway, the machine has now got two identical 1GB of RAM installed (one in slot 0 and one in slot 1). There is nothing in slot 3. And it boots with just this 2GB installed.
As I said earlier, I had installed 2.5GB and the machine failed to boot. I had put the original 512MB stick from before the upgrade into the empty slot 3. So, at this point and as far as I can confirm, the RAM sticks were no longer identical at least in terms of size. That stick is marked "512MB,SDR DIMM, H 64WHS STK 4603841". I looked that up online and found a website. I am not sure if it is an exact match. Mine does not say dell on it and like the RAM in the link below does not say whether or not it is buffered or unbuffered. Here is the link.
If you trust that the link matches, everything would seem compatible except that it does not say whether it is buffered or unbuffered.
I don't think the size difference is an issue, but I can't be sure of that.
And I don't know if you can mix UNB (unbuffered) and buffered memory and still boot?
Sorry if this post bounces around too much like flashbacks or flash forwards in a movie.