On Sun, Mar 8, 2009 at 8:39 PM, Rick <ellis at spinics.net> wrote: > In article <49B47E99.1090307 at hogranch.com>, > John R Pierce <centos at centos.org> wrote: > >>now, try taking out the OLD memory and putting in just the NEW memory. >>see how it runs that way. if this works, try with the new 4GB as the 0 >>bank, and the old 2GB as the 1 bank. > > Tried that before I posted and got the same results. > I assume the following in this reply: you are using DIMMs, one (or two) cards for 2GB and one (or two) cards for the other 4GB. 1) You probably did this, but until the above reply, it was not clear that this was your memory configuration: make absolutely sure that the memory timings on all your DIMMs are the same. If any one is off by even one in any of the settings, they will not work together. Period. 2) Your answer above was not clear: did the 4GB work by itself without the other 2GB? If so, the above is your problem. If not, you're in deeper guano that you think, BUT: 3) Some motherboards (many) will not accept different size DIMMs at the same time. If yours works with the 2GB alone and the 4GB alone but not both together, that's probably the problem and you can't do it at all on your present hardware. Also, by "running in 64-bit mode" (previous reply), do you mean that your are running the 32-bit PAE kernel or the x86_64 kernel? Some hardware doesn't seem to like the former, but that's just what I've read here before. (I use the x86_64 kernel....) HTH mhr