So, I have a nearly 3-year-old Inspiron 1720 laptop from Dell that serves as my main PC. This machine still has a couple of years of service left in it.
I run VMware at work all day and of course I would want to have plenty of system memory to avoid hard disk paging activity under this high memory load. According to Dell, the maximum memory capacity of this machine is 4 GB (2 GB in each of two slots). However, others have discovered that 6 GB works fine in the machine, so there is no problem installing a 4 GB module along with a 2 GB module. However, installing two 4 GB modules for a total of 8 GB does not work, as there is a bug in the BIOS that will keep the machine from booting.
I decided that 4 GB is not enough for my workload so I went for the upgrade to 6 GB. It worked fine. However, I wonder, to you lose any performance by going to 6 GB? Of course, in this configuration you have a mismatched pair of RAM modules. Does stuff like dual-channel access still work?