My servers are running FreeBSD 6.0 AMD64 without any problems on Quad Opterons and Dual Processor/ Dual Core Opterons. Initially we had the wrong kernel compiled so only 1 CPU was recognised, but this was picked up quickly - we now run the 64bit SMP kernel, and the forums have never been faster.

FreeBSD is an awesome OS - the ports system is easy - install portmanager and you can easily install ports using single commands - say goodbye to problems with rpm dependencies. :) It's also fairly easy to customise, and is secure.

I documented everything I did to set up a FreeBSD server, so if anyone wants help, let me know. :)

Also, I'm running Lighttpd instead of Apache - this is a fantastic webserver, much leaner than Apache, and is fast! It also load balances php by running php as separate processes - you've got to try it out to believe the difference in speed and reduction in server loads.

yeah that's the point for wider 64bit hardware driver compatibility it would probably save alot of hair pulling sessions :)

We did pull our hair out when we had to try a few RAID cards until one worked with FreeBSD. ;)

I have Dual xeons 2.8 with scsi and 2 gb of ram, and planning in a shrort time move all my forums to a new quad opteron.

I'm running my sites on dual core amd64 4400+ & 3500+ out of my studio, so far so good. I'm using Apache 2.0.58, php 4.4.2, and mysql 4.1.19 on xp pro other than needing to setup ioncube it seems to be running good.

Quad Opteron (DualCore) 265
120gb sata raid + 120 sata backup drive
CentOS 4.3
Cpanel
And no problems so far...

Some people may get confused...

You can have 64-bit CPUs (x86_64), but run a 32-bit OS. (x86)

I wonder how many people are running true 64-bit systems.

Just for the record, if you are going to run 64bit CentOS, be sure you recompile the kernal.

The kernal it comes with has a nasty bug that causes it to eat up swap for memory usage over 400mb, even if you have more RAM available. Caused me lots of trouble.

I'd probally run a 32bit os with a 64bit processor.

Jeje I think you just give me the answer to my ram usage problem...
I was clue less