Pentium 4's are fun because they get so hot, so quickly, that if you try to boot one with no heatsink, the overheat protection trips and the computer shuts off before it even POSTs!

They do POST, but can cut out before you can be sure the CPU/board is ok...

With the heatsink or a ballast placed on the CPU (no fan, no thermal compound) they hold up longer

@IceFogLights : Actually i seen those "MHz" led displays both with the jumpers, and in a cheaper jumperless version too. That one had the LEDs shunted into groups right inside the LED component, and capable of displaying only "HI" and "LO"

I just hauled 11 old computers off to the recycler.  Some of them worked and some didn't.  I pulled anything that could be of use, and went through and stole all the little multi-colored jumper shunts.  I went through my stack of hard drives, and found 10 that were duds and put them in the computers to go away.  Ran KillDisk on the remaining good hard drive (540MB).  Four of them were Socket 7 machines, four were original cachless Celerons, two were Athlons and one was a CRT iMac.  One Athlon refused to boot, like it couldn't detect a video card, and the other had leaked VR caps.

Also ran DBAN and restore on an old Pentium 4 laptop and dropped it at the thrift store.  While I was there, I found a Thrustmaster Top Gun USB joystick for $4 

I'm curious, did the iMac work?

Also semi recently, we found a couple unopened fiber hard drives.

I'm curious, did the iMac work?

The hard drive was bad, but it did power up.  Was evidence it had gotten wet though. The RF shield had started to rust and mold was growing inside of the case.

Ew, that's too bad.

While I'm here, I must mention a huge lot of vintage computers I got a couple of weeks ago. I discovered that my school was collecting e-waste, and putting it into this huge pile to display as an art piece. I spoke to someone who worked on it, and they said that when the display was over (which was a couple of weeks ago), I could take whatever I wanted from there. I took a total of 14 computers, evenly split between Macs and PCs, and desktops and laptops. I talk about the Macs here, and I'll show the PCs here once I get pictures of them.

Little more info on it.  It was a slot loading "5 flavors" version with the 350 MHz G3 and CD-ROM drive.  It had a 6GB hard drive.

Many of these old computers (including that iMac) came from school surplus.  Others came from other people I knew, thrift shops, or remnants of old projects.

Some of them, like the iMac had gotten wet.  They were stored in an old metal shed that leaked a bit.  Fall before last, I hauled a load of the CRT monitors they had come with to the recyclers.  Unfortunately, without them stacked inside, the roof had a hard time with snowload and started to cave in.  Made it into a nice water collector now.

I pulled out the old 486 tower to fire it up, but unfortunately it's a dud.  Failed power supply.  Turn it on and the power supply just buzzes.  Unfortunately I don't have an AT power supply handy.  It's an interesting computer with an interesting history anyway.

It's service life was spent acting as a mainframe/server at a village health clinic, where it sat in the back office and kept patient records and scheduling.  It was accessed by a terminal in the front office.  It ran SCO UNIX.  The motherboard is quite large, with a socket 2 processor socket, eight 30-pin SIMM slots, each with I believe a 1mb SIMM.  Aside from the keyboard connector and front light connectors, there's no built in I/O on the board.  It has 6 EISA slots and two ISA/VLB slots.  There was an ISA serial/parallel card, a EISA disk controller (floppy/SCSI) card, a 3Com Etherlink III EISA network card, an EISA external I/O card, and a VLB video card.  For drives it had the at the time standard 5.25" and 3.5" floppies, a tape drive and a 340MB SCSI hard drive.  It was retired in 1999 and somehow made it's way to me.  I may have the install disks for SCO, but I reparitioned the hard drive and installed MS-DOS on it, though I don't remember if I put Windows 3.1 on it.  The processor is a 33MHz Intel 486DX.

Since it appears to be toast, it will end up going to the recycler on the next public drop-off day.

That's a darn cool old computer. Too bad the PSU is shot.

I'd mentioned this one before, but finally dug it out of storage.  This old beige box used to be my sister's.  Despite about 10 years of cold storage since it was last turned on, it still works.  The system clock was only 3 hours off.  The 14" NEC CRT monitor that was pared with it unfortunately doesn't seem to work anymore, so it's shown here connected to a 17" LCD monitor.  It's running Windows 95 (original release) with Microsoft Plus!

Here's a shot under the hood with some specs.  Interesting little computer.  The motherboard is a socket 3 PCI board made by QDI, and based on the UMC UM8881F chipset.  There's 256K of cache.  The processor was originally an Am5x86-133 but I accidently burned it up, so now it has an 83 MHz Pentium Overdrive.  I have an Am5x86 (standard chip, no adapter board) on order, though I have to track down a heatsink/fan that fits it.  It originally had 8MB of RAM, but is now loaded with a whopping 64 MB.  For drives, it has the standard 3.5" floppy, and an 8x CD-ROM drive.  It came with a lethargic 2x drive, but since I had a faster one handy, that had to go.  It originally had a Seagate 420MB hard drive, but I replaced it with a 1.2GB Quantum Bigfoot.  For ISA cards, it has a Sound Blaster AWE64 sound card and a USR Sportster 33.6 modem.  The original video card was a 512K Trident TGUI 9440 but I replaced that with a 1MB TGUI 9680 for higher resolution and better stability with increased bus speed.  I also just dropped an SMC 10Mbps PCI ethernet card in it.

Ah, nice! With an Am5x86, this machine will be VERY similar in hardware to my 486 machine. Interesting to see a Windows 95 sticker on it - these semi-generic 486 machines usually didn't have any stickers besides the occasional one identifying the outfit that built it.

Here's one of the PCs I saved from recycling, an Epson ActionNote 4SLC/33 from 1994. 33 MHz 486SLC, 4 MB of RAM, 160 MB hard drive, floppy drive, and a dual-scan passive matrix black and white 640x480 display. No CD-ROM, no pointing device, and no sound capabilities. It uses a Dallas DS1287 clock chip with an internal battery, which was unsurprisingly dead, so it was impossible to boot because the BIOS forgot the hard disk parameters as soon as you restarted after setting them. I found a web site detailing how to hack (both phyically and figuratively) into the chip to attach an external battery, and I did so successfully, using a 2x AAA battery holder which I placed in the main battery compartment. I then installed Windows 95 without issue. With 4 MB of RAM, this isn't really suited for 95, so I'm gonna replace it with MS-DOS 6.22 and Windows 3.1 eventually.

One minor problem has surfaced - once the machine has been running a while, the keyboard stops responding. It seems to electrically disconnect from the motherboard, as occasionally it comes back to life, and the Num/Caps/Scroll Lock keys blink, like they do when booting. I had removed the keyboard to perform surgery on the clock chip, so I'm hoping I just didn't secure the connections well enough when I put it back in. Otherwise, there may be a cold solder joint or simply something wrong with the motherboard, which would suck.

The Windows 95 sticker was peeled off another machine.  That's why it doesn't really stick.  May have come from the same Pentium machine I swiped the video card from.  There used to be a brand tin (ISG) on the case, but that fell off at some point in time.

Could be an issue with a loose connection, or some other problem.  The Pentium 4 notebook I mentioned above had a display backlight that would flicker once it came up to operating temperature.  Could have to do with the internal work you did too.  After I got my iPad, I decided to try to swap the hard drive in the little Acer netbook I used to have, so I could attempt to install Ubuntu on it.  To swap the hard drive, the WHOLE THING had to be disassembled.  After swapping the hard drive out and back, the Wi-Fi switch was broken off, and I couldn't get the trackpad reconnected, so it had to be used with an external USB mouse.

Well, I removed the keyboard, and one of the connections to the motherboard came out with barely any force - my fault. I resecured it, hoping that would be the fix. Alas, it happened again after running for an hour or so. This time the keyboard came back to life, but all the keys were mapped to completely different letters/functions. I opened it up again, and made sure the two connections were really secure. It's run for over an hour without issue so far, so my fingers are crossed. If it does it again, this will go up on eBay.

Well I had a pretty nice score today, in throwing away deom older computers (which I never like, but you must) I rescued 2 fiber channel drive with SCSI controller, and one of them was in a Cooler Master drive bay which is pretty cool, a FireWire card and come older case lights and fans.  Also kept what I believe to be an older phone server and a Windows NT PC that seems identical to the machine that a threw away and it has 2 Cooler Master drive bays, so I would think it also has 2 fiber channel drives in it, pretty cool.  So those are 2 more machines to add to my collection.  Also maybe 4 years ago I managed to get the NT machine online and browse eBay, I wonder if it will still do that.

EDIT: Also got 3 floppy drives, 8 optical drives of varying ages, a total 7GB of assorted RAM types and 2 Rambus Terminators with 2 Rambus RAM sticks worth 256MB of RAM each.