The point I tried to make with my last response is that you're not checking the integrity of your components properly! Why do I say this? How can you test the integrity of your HD when you can't account for the integrity of the parts that carry the information from the hard drive to the visual representation of it on your monitor? You need to work your way down the component chain -- one by one -- generally without skipping links.
How do you test your PSU? One should test their PSU when the computer is under load. To do that one needs a digital multimeter and the comfort to work with "live" wires while the computer runs PRIME95, or the likes, over the course of several hours. Now you could test it in a different unit but that computer must have power demands that meet or exceed your computer's.
From there I would recommend booting into a preinstallation enviornment of some sort -- an OS-like enviornment that does not require a hard drive. you might be able to use UBUNTU or BartPE but I'm not sure because I don't use either. The premise: booting into a PE will theoretically allow one to exclude the software from the potential sources of error. That's why memtest, seatools, and other diagnostics boot straight from the CD. Make sure you disconnect your hard drive and any other component that would be unnecessary for the computer to operate during this period -- the more parts you have connected the less likely you are to pin point the source of error.
Memtest tests more than just RAM, certain errors that occur during a memtest have been shown to be a result of something directly unrelated to RAM.
You have a Venice processor, meaning the memory controller is on the processor's die itself, so one may receive a memory error when it's really the processor... or one may receive a processor error when it's really the memory.
Frankly, at the moment, I don't have the time walk you through a diagnostic procedure. I'd like to help but school and work have me pinned down. I'm sure someone here will be more than happy to help you. Remember to properly traverse the chain of command, as you cannot blame one component if it depends on another.