Let's just say it's a piece of crap Dell prebuild computer that:
Loves to freeze and restart itself on a cold boot (happens within 5-10 minutes after windows is loaded, minutes varies on load. Or freezes during a memtest86+ run after booting from a cold boot with about a 1/5 chance that Memtest will detect errors).
Did you run comprehensive hardware diagnostics that Dell provides for free with every computer on its hard disk, on a CD, and from their web site?
Numerous assumptions are based in popular myths; not found in hard reality. For example, you have assumed a PSU is the entire power system. It is only one component. What determines when a computer starts or stops? Power controller.
Already posted was how to have useful answers from those who better know this stuff.
The foundation for any computer is its power system - more than just a supply. Nobody can provide a useful answer if you do not first provide numbers. That means a multimeter even from Wal-Mart, K-mart, Harbor Freight, or any store that also sells hammers. Measure six wires. Report the numbers. Have an answer without any more doubts. Labor is about a minute - not including the much longer time required to post those numbers.
You have no useful answers due not providing important facts and numbers.
For example, how does a diagnostic find defective or intermittent hardware? Execute diagnostics in a room above 100 degrees F. That is an ideal room temperature for all working PCs. Heat is an ideal diagnostic tool to find defective hardware. Especially to find defects long before those defects become obvious months or years later. This testing best done with comprehensive diagnostics only provided by the better computer manufacturers.
Well, did the Geek Squad provide voltages (to three significant digits) from those six wires? Why not? You paid them to check out the machine. That is the first thing an informed tech does. Where is their report with numbers?
BSoD 1A defines a memory management failure. Where? Well, again, you shorted your help of hard facts including four other numbers and the worded description. BSoD D1 reports details about some code (probably a driver) that attempted to violate memory protection found in better computer architectures. Again, other numbers and text would have resulted in a much more useful reply.
None of that says memory is defective. Those error codes define numerous potential problems. A list that gets much shorter if you had used the multimeter, viewed the system (event) log, executed comprehensive hardware diagnostics (including at elevated temperatures), and provided BSoD numbers.
Your Dell is literally screaming useful facts. A good computer tech should have been able to list the shorter list of suspects. Using what was provided, this short post is all that can be concluded. Your replies will only be as useful as facts that you first provide.
Step one always starts with getting the meter and asking for instructions on that long one minute of labor.
