I have a machine that I originally built 4 years ago which has started to have some....shall we say interesting problems. Essentially, it likes to blue screen at random points, for varying reasons. I've had it blue screen during games, during nothing at all, during internet browsing, even OS installation. In the hopes of diagnosing/fixing the problem, as well as updating the system, I recently went through and replaced the power supply, motherboard, RAM and cooling, to no avail.
The most common error seems to be IRQ_NOT_LESS_OR_EQUAL, but I have seen errors ranging from "bad pool caller" to "trying to write to read-only memory".
Windows 7 (although errors appeared on XP too)
Intel Q9400 Quad core 2.67 GHz
2x 2GB OCZ 1066 RAM
Power Supply - OCZ|OCZ700MXSP 700W RT
ATI Radeon HD4850
Gigabyte EP45-UD3P Motherboard
LG GS-H55N CD/DVD Drive
I'm quite confused at this point about what could be causing the problems. The only hardware I haven't replaced is the graphics card. If I can get some indication that the 4850 is the cause, I'll be happy to get rid of it to help solve this persistent problem.
Unfortunately, the only way to know for sure is isolate every single component, one at a time.
Beg, borrow or steal components where you can.
When we ran PC's at work id always have a test system. That way i could test anything i needed quickly and easily. Of course it gets a little hard when you have different standards in ram, cpu and gfx etc, but its the only way.