After replacing 1GB RAM module with 2GB one in Asus F3Sg laptop, thus taking total RAM to 4GB I started experiencing weird issues.
Applications would crash, causing numerous logical errors on HDD. (64bit Ubuntu, ext3, latest BIOS).
However, memtest86+ highlights no issues and as soon as I revert back to 3GB of RAM issues disappear. Both 2GB modules (PC2-5300) seem to be healthy and work perfectly when paired with 1GB module, but cause aforementioned issues when used together.
So question is - is there more comprehensive set of tests than memtest86, possibly allowing me to reveal the underlying issue (motherboard? RAM? HDD?)?