Surplus/discard auction buy of 24 Dell Optiplex cases. Picked them up at just over a dollar each, since harddrive, powersupply and most cd/dvd modules removed. Still happy to get them, as other bidders passed due to junk condition and lack of usable parts.
Of note is these all had Pentium D pinless CPU. The good news is they open out like a suitcase with the flip of the latch, so quick to get to the goodies. Also, there is a humongous heatsink, about five inches tall and 3 inches square, with a huge copper plate with the aluminum fins . Again, only some had any memory sticks, but adding 25 motherboards and cpus and some gold memory to the collection is building toward a good pay day.

The boards by themselves would cover your purchase cost and leave you with at least 0.25 per PC profit. The other recoverable components are gravy.

I often am required to make corrections in my previous avowals: like when I told the preacher and assembled audience to see a woman get married, and I said, "I Do," for some reason I usually wound up telling the judge later, that "I didn't". No reflection on the lady (s): just pointing out their poor judgment in choice of husband material.
I need to correct a couple of my statements above. These units were GX 620 rather than 630. Also, the ones that opened like a suitcase were four digit models, rather than in the hundreds series, and there were only two of those. Since those two were complete with everything except the harddrive, I put them back for testing with a harddrive installed instead of junking. The others that I did scrap were large towers who popped a side off with the push of a button, so quick to dismantle. Only six had the power supply, with Cd/DVD intact, while another 5 had only the CD.
Of note is that the ones I stripped all had Celeron D processors, a pinless one. While the D was apparently a good Chip, it was a dual core which produced a huge amount of heat, and required a 1 3/4 pound Cu/Al heatsink. The stripped GX620 were lacking in memory sticks.
Here is a rough breakdown:
Cost of 24 units $31 plus tax and fees, Total $36.50
Kept 8 units, so cost of ones recycled, $24. 20 (figures not precise)
Time to remove 9 screws by hand driver 2 to 3 minutes less than an hour total

Value of steel housing (large tower) approximately 20 pounds @ .03 $0.60 times 16 total recoup $9.60

16 pinless CPU weight slightly over 3/4 pound, at $4.50 per lb, about $3.50

16 metal socket green motherboards, roughly 1 pound each, at $1.80 per pound, total $28.20

16 Cu/Al heatsink, 1 1/2 pounds each , total 24 pounds@ $0.50 per pound,
total $12.00

30 pounds of power supply with wire, DVD/CD whole, @ $0.15 per lb, $4.50

Total recoup: approximately $56.00 on stripping 2/3 of the units.

Notes: usually these units would have a couple or three gold memory sticks, at about 40 cents each, and two or more gold finger cards. Extrapolating these figures to the entire batch of 24, if I recycle all 24, I expect to get approximately $90 scrap value

‘Put them back for testing’

That’s the way to do it.
Actually I seek out archaic junk intentionally.
Many people in scrap (I was there once) start By seeking out systems that have the high value parts for scrapping.
These are generally the most reparable systems you can buy.
Radio Shack may no longer be down the street but there are hundreds of qualified licensed sellers of similar components on the internet. Everything from capacitors and resistors to filaments and clocks and crystals!

The older the machine the larger the components!
You can find 4040s and 8008 systems in bulk for under $30 each. DOA.
A few dozen dollars and a few days of work any you can easily make a working system with minimal soldering. As long as the cpu works you can fix it. Anyone with some time and effort can fix it.
A working 8008 system with a copy of CPM 0.9 (free on the net) starts at $500.
An 8080 system with half a meg of ram will fetch a grand.
There’s a good reason why though.
As I point out often CPUs like the 8080 and i486 are still in regular production. Every smart phone with a screen larger than 3 inches has an x86 controller in it.

Today running >1990s manufacturing equipment requires special cards to use in modern servers. So they drop a few grand on the server and then another few grand on a plug-in card, and hundreds more on controller software.
Walk into any major old-tech factory with a fully working 8080 from any company with CPM or a DOS and they’ll likely pay you a grand on the spot cash (cheque).
The numbers shrink after the 386 era but the fact is any computer is worth more as a computer than scrap. So are parts
An original 3D FX card can fetch $50+ working. $25 doa. Or $6 of gold finger card.
A dead Toshiba satellite laptop with a core cpu will get you $50 as is. Or about $15-$20 in scrap from various Places after you dissect it.

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