Clearly step 1 is going wrong somehow, but, I mean, I'm a fairly typical HN poster, you know, I've got at least intermediate-level search skills, you know?
One of the things I always do these days is look up the memory compatibility for the motherboard I've selected, and then only buy off of that list. There are so many variations in just DDR4 2400 memory, and matching up all the parameters (timing, latency, etc.) is a hassle.
Theres two things I hate dealing with the most when it comes to PC building. Those are (1) building a PC from scratch from all new components (2) debugging a PC when a part died
This is because diagnosing the problem and identifying what was wrong could be so many possible things. Back then as well we also didnt have these nice tools like pcpartpicker.com, all of these great youtube tutorials, just a bunch of forums to debug issues.
PC not turning on? Maybe the power supply is not working. Or maybe its the power button itself is having a problem, the switch might have disconnected. Or maybe the wall power outlet is having issues, and maybe can't handle the load. Maybe you changed out a part recently and didnt connect the pins correctly, or during transportation something disconnected. Have to manually check every wire. Are the fans spinning at least?
Is the OS not booting? Okay, is BIOs at least running? Before that, can you hook up a keyboard into the PC? Is that even registering? Does it need an adapter (older PCs didnt use USB 2.0 ports for keyboard mouse). Do you have compatibility issues with hardware components?
Is the computer registering the RAM? Did you check if you slotted it in correctly, by shoving the pins far enough in and latching it? Its possiblethe RAM you recieved was dead on arrival. Try swapping the outlets and see if anything registers
When you changed the CPU did you make sure you didnt bend any pins? If you did your SOL. Maybe you put too much thermal compound between the fan and CPU.
Between all of these steps, did you make sure to ground yourself and prevent static charge from frying your motherboard?
Is your OS booting but your having software issues? Run safemode and find the culprit.
The list goes on and on and it just never ends. Narrowing down the specific issue was always a PITA.
I used to go to a screwdriver shop (in Federal Way?) that had some memory and a power supply sitting around at the counter. They would POST a new CPU and board in front of you before you take them home. Less stress than ordering from some random in the Computer Shopper phonebook.
Had it happen again a couple years later but that time it turns out the motherboard was just DOA. But yeah the time spent confirming that the motherboard was the culprit sucked, and required another PC to swap parts with.
I just recently put together a new PC and I was getting close to done. I plugged everything in before putting the side panels on, hit the power button and...nothing. No fans, no beeps, nada.
Okay, I'll just disconnect the ATX power cable from the motherboard and short PS_ON to ground and see if the PSU fan will spin a bit...nothing again.
Hmm. Maybe the modular cable is bad? Google the pinout for Corsair's "Type 4" PSU to make sure it's what I assume it is, drop my bit of wire down the correct pins directly on the PSU, jam my multimeter probes down a 12v + ground and...hell yeah, getting 11.something volts.
Okay, bad ATX power cable, call Corsair, wait a week, problem solved. My wife was watching me do all this on the breakfast bar and kept asking "how did you know to try that?" and I really didn't have a good answer other than "been doing this or watching my dad do this since I was 8".