My ram upgrade nightmare . . . I have a classroom of 24 Dell Dimension 4100s PIII 1Ghz machines that are getting a ram upgrade. They require PC100 or PC133 non-ECC x64 chips and can handle up to 512mb total. They were running on 256MB of ram consisting of one 128MB PC133x64 (high density? chips on one side) and one 128MB PC100x64 (low density? chips on both). After checking compatibility, I order 48 Kingston Value Ram 256MB PC133x64 non-ECC (high density?) and try to upgrade my first machine. It fails on memory check before bios launches even. I upgrade the bios and it recognizes both chips and continue to upgrade systems. 50% of the machines take the upgrade without problem, but the other half fails with half of those accepting one chip and the other 6 failing to recognize either new chip. RAM that works in one machine will fail in any machine that fails to recognize the chips so it doesn't seem to be bad chips. The old RAM still works in machines that failed the upgrade so it also doesn't seem to be the motherboard. All of the machines are the same age with the same setup built in the same batch at Dell. Any thoughts?