Amber light/aux pwr

I'm writing in regards to my dilemma, I have a xps 8300 I've only had it a short time. Sense yesterday I've been unable to boot my machine with out getting the blue screen of death? It's saying that it has stopped (desktop) (error) and I guess according to Dell Tech Support the error code is for determining the problem and supposedly I needed to re-seat the memory modules along with dis/ then re-connecting all hard drive cables and re-boot! Well didn't work and I noticed while inside my case that theres a steady amber light on the motherboard above the (pwr aux) and that got me thinking about beep code and the lack of every time I try to boot which I found strange? As a hobby I build desktops to spec for clients and knowing I haven't ever seen a amber light on the motherboard that resulted in a positive outcome!! I've run diagnostics from BIOS on my machine both a fast scan and then the thorough scan which takes 30 minutes lol yea right and it's able to complete the tests and passes everything including the Hard Drive sector test?? OK, that doesn't fix the problem so now I have to look from the motherboard to the power supply to determin if the p-supply (460w) is faulty by checking it with a voltage meter and if it's not the p-supply then is the motherboard defective? Has anyone had this problem as well?? Thanks A TON:) Mark