For those in the UK (where this offer is unavailable), the below may be of interest.

http://www.ebay.co.uk/itm/Intel-Xeon-Processor-5150-4M-Cache...

£1.99 + £1.50 P+P UK mainland.

well its 7 years old and has quite a massive power consumption compared to its speed by todays standards.

Bought two (from another seller as the ones linked weren't available). I have a 2006 2GHz Mac Pro; These will drop right in and extend its life a bit more. I mostly use it as a Boot Camp machine for Windows games these days so it'll make a big difference. Thanks for posting.

Price mistakes happen all the time and your orders get cancelled...

It doesn't look like a mistake if you see the pricing history. http://www.cpubenchmark.net/cpu.php?cpu=Intel+Xeon+5150+%40+...

Anyone knows why the price bounced from $99 to $770 in 2011?

It seems to use Newegg and Amazon as sources. A common trick is to just leave an item at high price when you don't have it in stock so no one would buy it. If someone did buy your item at that price you could cancel the transaction or go out of your way to get hold of the item.

So I guess at that point they were the only ones with the item "in stock".

I never thought about upgrading the CPU in an old machine... That's the main bottleneck in my gaming machine. trawls eBay for cheap LGA775s

They're (almost) half that on eBay[0].

0. http://www.ebay.com/itm/271196427487

Bought two! One for me and one for my homies.