I am troubleshooting one of our Optiplex GX270 computers that failed on us here at the office. The diagnostic lights on the back (A, B, C, and D) are lit in the order Green, Yellow, Green, Green. That's Green for A, Yellow for B, Green for C, and Green for D.
This diagnostic "code" is not listed in the Dell OptiPlex GX270 Systems User's Guide (located here: <ADMIN NOTE: Broken link has been removed from this post by Dell>).
If anybody knows what this error code means, or could link me to a document that explains this error code, I would greatly appreciate it.