There are a number of possibilities. Perhaps your Digital Audio is running OS X which is less tolerant of non-standard manufacture RAM where the design did not adhere strictly to standard specifications. Perhaps your sticks are not all of the same manufacture. Al Poulin On Jun 29, 2008, at 1:34 PM, Mike Bechtold wrote: > Yesterday, I picked up three sticks of 512MB PC-133 RAM to max out my > Digital Audio from a local computer repair guy. I took a G3 iMac with > OS9.2.2 with me as a portable memory tester, and that system > successfully recognized all three sticks. > > But when I installed them in my G4 Digital Audio, one stick prevents > the > system from booting past the post chime - but only when it's installed > in the RAM socket right next to the first PCI slot. If I install in on > the third slot, all three work fine. > > I'm a graduate EE with thirty five years of electronics experience, > and > I've dealt with a lot of funny stuff. But this one's got me puzzled. > I'm not worried as long as the system works, but curious. Does anyone > have any suggestions as to why this might be happening? Is it a > capacitive loading issue, something in the mobo, or ??? > > Thanks for any enlightenment you might provide!