Ok, I know this is outside of the norm for this page, I don't really care.
Backstory: I buy things from estate auctions on hi-bid. Nobody else bid on this so I got it for the minimum bid, $2.50 USD.
It was missing the hdd, and it was in a filthy barn.
Side note: auctions are generally "as-is, where is" that means you pick these items up at the location of the estate, they usually pull things out and organize them, but they don't clean them or anything usually.
I have an extra IDE HDD, so I threw that in and tried to install Windows XP. I got errors halfway through saying "setup cannot copy the file:"
Then I got it to go all the way through, but it won't boot.
Then I got a system error that the HDD is not present.
I tried an IDE adapted SSD, still not recognized.
Then I got the HDD recognized again.
I figured I would check the ram: 1x 256MB. I threw in 2x512MB, that's a neat trick.
I also swapped out the cd drive since it was having a hard time opening up anyway.
Now I'm back to, "setup cannot copy the file:"
Maybe a bad CD burn? Idk, it's been awhile since I've done this.
If the HDD is intermittently not being detected even in the BIOS, there's probably an issue with the hardware involved. Flaky IDE port on the mobo? Bad power or data cable? Overheating? Or, as someone has already suggested, capacitor plague?
I can't remember whether Dells of that era had manufacturer hardware lockin issues or not.
I swapped cables and etc. It turned out to be a bios setting for the drive. I think the bad battery just caused the settings to get wiped.
Why it was intermittent like that makes no sense though, but it's good after I figured out how to enable that drive number.