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Mixing and matching Xeon Processors?

So I recently came to acquire this beast. It's a beautiful 13-year-old IBM Intellistation Z 6221 with a 3.2ghz Xeon processor. I really dig the IBM styling... it's also ridiculously modular, not even requiring a screwdriver to rearrange drives. Unfortunately, due to its age, it's only 32-bit. In fact, it came with one (supports two) of the fastest and final 32-bit CPUs of the Xeon family.

The first step was to find extra ram to fill the 4 slots. This would only ever max to 8gb, so I needed 4 2gb DDR PC2100 dimms. Not so easy to find any more and prices are going up... either way they were sourced from eBay. I also, now that I think of it, accidentally sold the black floppy drive because a collector wanted it. It's now silver... and doesn't look too bad... but I'm on the hunt to fix that... Or maybe I'll put a zip drive in there...

Next step was to fill the second CPU slot... Thanks to the modular case, no screws were harmed during the dismantling of this product. As you can see below, the naked socket is neatly protected by a plastic shield that plugs into the heat-sink socket. There is, of course, no heat-sink; as there is no CPU in that second slot by default. You could choose this as an option when purchasing the unit.

It turns out that I had another Xeon desktop, in the form of an HP MLxxx. Although this was only a Xeon 2.7ghz, I'd read online that you may well be able to mix CPU speeds? First thing was to remove the CPU from the HP. This turned out to be very easy as its case was also very modular.

Instantly you can see that the heat-sink is different... the IBM used case-mounted fans with passive CPU-mounted heat-sinks, whereas the HP used heat-sink-mounted-fans. I inserted the CPU into the slot on the IBM's motherboard, but the heat-sink shape was different to the bracket mounted on the IBM motherboard. The heat-sink from the HP would not fit in directly!

I quickly tried to remove the bracket from the HP motherboard, with the intent on transplanting it into the IBM. After a lot of effort, it came off (the screws HP used were nearly torqued in!), but then it wouldn't fit in the IBM! It was too wide and long and actually wouldn't fit between the rows of capacitors. So much for industry standards!?

Ok... whatever... I mean how quickly can these things heat up? I'll just hold it in place for a quick test... before I mangle the heatsink to fit. Nope. Turns out the IBM wont even power up with this CPU in the second slot. Is this a fail-safe mechanism because the CPUs aren't matched? Is this CPU a dud? (I hadn't tried it prior...) Dunno.

Make sure the CPUs match!

Off to eBay, I found an identical SL72Y processor in England. It took a few weeks, but it arrived. Again, prior to hacking up the heatsink to fit, I thought I would install the CPU quickly as a test to see if the machine would POST.

Oh wait... it wouldn't just slot in... oh wait... look at those bent pins! I still don't know if it was the beer or the fact that it came off its little foam pad already-bent, but it required about 30 minutes of pain-staking twiddling with a pair of tweezers to get the damn thing in. DO NOT RUSH THIS PROCESS. At one point I thought all was lost as it just wouldn't mount... but after a lot of adjusting it went in.

A bit of hacking was then required to fit the HP heat-sink. I had to hack pieces out of the braces that screw down to the motherboard. I then had to bend a few fins on the actual heat-sink so they wouldn't ground-on or damage the rows of capacitors placed so nice-and-close to the CPUs. And then... it just freakin' worked... and the machine finally loaded Chrome at a proper speed on Linux Mate 18. Now to find a more-appropriate OS to run on this slightly ancient hardware!