Hi Humpy12345, welcome to itsallPC

Things like overheating, faulty capacitors and faulty graphics cards absolutely do not lead to predictable shut-downs occurring after a specific event, such as you are experiencing; they lead to unpredictable, even random reboots. While the memory and hard drive could be responsible, it is most likely that it is a software problem.

Windows update following a fresh install could include a large number of fairly deep security and robustness updates. If you have a problem driver or piece of misbehaving software, that is the most likely cause of a reboot during a Windows update.

Your current issue is because you bumped something while you were tinkering in your computer. You could have done any of the following to cause your current situation:

• Dislodged the RAM
• Dislodged the graphics card (if there is one)
• Knocked out one of the motherboard power cables
• Damaged the RAM
• Damaged the motherboard
• Damaged one of the IDE/SATA cables

This is based on the fact that it wont boot, but it can still beep. You need to be honest with yourself here. If while you were inspecting capacitors, you broke one off, it's curtains for the motherboard. You would do yourself a huge favour if you stop jumping to conclusions, because your current decisions look pretty irrational to an expert right now

If you're able to solve your no-boot problem by plugging something back in, I would strongly recommend the following:

• Test the memory with Memtest86+. Many experts leave this out, but it's absolutely important to confirm the memory is okay. Trying to work out what's wrong with a computer with faulty memory is is like trying to solve an equation with a calculator that adds a random number to every operation.
• Test the HDD. You could do this at a low level, but a full Check Disk test will tell you pretty quickly if there's a serious problem. This is the "attempt to recover bad sectors" test; make sure it does this, otherwise it's just a file system check.
• Confirm from the device manager that all the drivers are installed. Install any missing drivers. Make sure all the following drivers are fully up to date: Motherboard/Chipset, Graphics, Sound, Network.
• Make sure your Windows is updated to the latest Service Pack before using Windows Update (currently, Service Pack 2).

If you require any further assistance with any of the above, please post back before you jump to any conclusions!