Weird memory issue

[Aviator_14]

I upgraded the RAM in a friend's old Dell Dimension 3100 with Windows XP. It was really slow because it only had 256mb of RAM installed. I upgraded it with (2) 512MB sticks of DDR2-533 RAM, and after putting the RAM in and turning on the system I notice that the system restarts multiple times and is unable to fully boot. One time I even got a BSOD. I immediately suspect that the memory I installed was defective.

I then ran memtest, one stick at a time in the same memory slot (the bottom slot), and both sticks successfully completed the test without any errors; However when I ran memtest with both sticks of memory at the same time in both memory slots, Memtest was really slow and kept looping back to 0%, and after a while came up with an error that said "unexpected interrupt - Halting," and the system freezes.

At this point I suspect that the motherboard or memory slot on the motherboard is defective, since each RAM stick passes in one slot, but not in both slots.

But, when I put the original RAM back in (a single 256MB module) it passes Memtest in either the bottom or top slot. At this point I am totally stumped and don't know whether the problem is with the memory or the motherboard.

Could it be that the computer is picky with what RAM is inserted even though it is compatible?

[Train]

Those 2 sticks are not close enough if manufacturers tolerances.

What crucial says.
http://www.crucial.com/store/listpar...203100&Cat=RAM

Why I always buy a new matched set of ram.

Mismatch can cause:
1. A no boot situation
2. All kinds of hair pulling errors
3. What we want. It works just fine.

[rockinup1231]

OEM workstations like those tend to be very fickle about the RAM they will accept. Typically speaking, the RAM you installed is the correct kind for that workstation. However, a number of different factors (supported voltage, timing, high or low density, etc.) the memory controller was not designed to handle could cause problems.

Another thing that comes into play when two sticks of RAM are installed is dual channel mode, which could have additional implications for the stability of the system, especially if either DIMM was manufactured by a different entity.

So you might try matching DIMM's if you aren't already doing so, or find more known good, similar memory to try as a pair in that machine.

[Aviator_14]

The 2 RAM sticks are from the same manufacturer and have the same part number.

[rockinup1231]

Then you will want to find RAM the motherboard certainly supports. With Dell that is usually Crucial but it can vary. A quick google search should give you some ideas.

[Midknyte]

Did you check for a bios update? Sometimes that helps with ram compatibility.