I don’t understand computers

I’ve been building PCs for as long as I’ve been into computers (early nineties) and they still baffle me.

Yesterday I installed a new graphics card on my office workstation, and the PC didn’t POST the first time. So I power cycle it, and it POSTs, but throws some “safe mode” BIOS error.

So I hit F1 to reboot in safe mode, and it’s back to not POSTing. Now I’m thinking the graphics card is the problem, so I take it out, and try the old card. Same thing. So I take that card out, and use the onboard graphics, still no go.

Now I’m getting annoyed that something else is fried. So I look at the motherboard Q-LED indicators. These are four lights on the board that indicate a specific pluggable hardware (ie the 4 things other than the motherboard that can fail) issue, either CPU, GPU, RAM, or boot drive issue. The RAM light is on!

I check the RAM sticks, they’re all stable and fixed in their slots. But like any good PC builder, I take each one out, check for any dust etc, and reseat them. Power on, still no go, and the RAM light is on.

Now I figure one of the RAM sticks is dead, so I take two out, and power on. Success. So, one of the ones I’ve taken out is dead. Shut down, replace the two working ones with the other two, to confirm this. Power on, and it POSTs!

So I turn it all off, add the original two sticks back in, turn power on, and now it all works. I even try rebooting a few times, to see if I can get it to fail again. I go as far as to shut it down for 3 hours, then start it up again, and everything just works.

I don’t understand computers!