> > I've just run memtest86 a few times. I ran it with all four memory > > modules in and got errors almost immediately. I ran it on each module > > individually for one pass and I got no errors. I guess I'll try it in > > pairs. Is there any reason why using both memory channels would cause > > trouble? You may just have hair or dirt in a socket. You might also have problems with the bus load - if the chips (or board) are marginal then the more RAM on the bus the more the load may be out. Also check the manual as some systems have rules (notably some AMD ones) about not being able to use all the sockets with the highest speed RAM. > If you put in more memory than the Motherboard has access to, then the > unused bits would present either duplicate data with somewhat different > timing, or if the extra address bits are floating, then random data > would appear, as one or more boards are misaddressed. This could cause > such a problem. Modern memory is a lot smarter than that and the connecting bus somewhat more complex than twenty years ago 8) Alan