Got my Quad Opteron board mounted up in a case now.

Going to call this Quadzilla from now on.

Definitely getting your money's worth out of that box. 😀

I'll split this into 2 posts. These are older servers, my current one will be posted later.

My first server was a 2nd hand Compaq Proliant 800. It came with a bunch of files on it from an insurance agency. I'm not malicious but I thought it was funny they left that stuff on there. I'm glad they didn't destroy the hard drives like some crazies do though - they just should have been wiped.
This machine uses the 440FX chipset. It started as a single Pentium Pro 200MHz 256KB, later upgraded to duals and then to dual 512KB versions. Dual 4.3GB 7200rpm Seagate ST34371W SCSI drives - those are still my favorite sounding hard drives. I had some fun figuring out the best way to partition them for parallelism. RAM limit was 512MB unbuffered ECC, I don't remember if I filled that or not. It ran Redhat 7.2 very well, providing various network services and light website hosting. When I tried a later version of redhat based on the linux 2.6 kernel, it fell down hard. That OS expected tons of RAM. I downgraded it back to Redhat 7.3 and kept it updated with Fedora Legacy. It was reliable and I was happy.
This machine had a lot of weird quirks about it. In the picture you can see a sticky note I had put on the front saying that I needed to insert a floppy disk in order to unlock the keyboard. That's just one example.
At one point I killed the keyboard port by hotplugging it. Learned that lesson, and found an ebay replacement for the motherboard. The seller probably felt lucky that anybody bought the old thing, so he went beyond and loaded it up with accessories including the 512KB CPUs mentioned above. Bonus!
It was finally retired when the PSU started acting up and I was also getting random overheat errors at POST which kept it from booting.
It's very picky about video cards. It will refuse to boot with most. This makes it problematic to use as a retro desktop PC.

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Temporary server after that was an FIC PT-2200 socket-7 board with i430HX chipset, P200MMX running redhat 7.3. 128MB RAM. Quite a step down from that PPro rig, but it worked.

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My nephew wanted to build a gaming PC for himself, and informed me of a couple motherboards he found in the trash. I traded him a newer, more suitable board in exchange for the 2 he had found. One of them was an Intel L440GX+. Dual slot-1 440GX, onboard SCSI. It was found with an "Intel Confidential" P2 CPU, and the motherboard BIOS reports that it's "Not for Release". I tried flashing it to the latest but it still says that. I had quirky issues with it's CPU compatibility, but found a pair of Katmais that it liked and used the 4.3GB SCSI drives from the old Proliant. This setup could handle a current linux distro, so it ran CentOS 4. It eventually ended up with 1.5GB Registered ECC PC100.
More recently I tested it with a pair of 600E Coppermines, thinking of using it for a file server, but I decided I wanted something faster. In this build I tested it with a pair of more modern hard drives and a GbE card. Power consumption of this system was surprisingly low, around the ~45W range.

For years I had some heavily-specced system humming away 24/7 because I sort of felt I had to, for nerd cred or whatever.

Last year though, I went low-power, and haven't regretted it.

My main server is an Intel Atom D525 based mini-ITX system with a 320GB 2.5"HDD, running Ubuntu 12.04 LTS. Also I have a QNAP TurboNAS with 4x3TB drives in RAID-5. About the heaviest task I use the server for is on-the-fly re-muxing of 720p MKV files for playback on my AppleTV, and it manages that alongside hum drum DHCP, DNS, VPN, Plex Media Server, etc no worries.

If this system stops working, I'll probably go to one of those Intel NUC boxes and save even more space and power!

My next server has turned into a bigger project than I originally intended. It will do file serving for the LAN, automated backups, possibly a database, and whatever other miscellaneous functions I don't want tied to my desktop. It will also serve Minecraft - there's a few kids in the family who play it constantly and I'd like to to play it with them once in a while. I might also set up voice chat on it, I haven't really looked into this.
I want to emphasize power management, since like most home servers it will spend most of it's time idle.
The main challenge is that I want it to roar to life when needed, but reduce everything to a low power state when it's idle. I don't mind a machine that guzzles electricity when it's doing work, I just hate when they suck power to do nothing at all. So my goal for this build is a machine that dynamically scales itself according to demand.
The hard drives will be activated on-demand, not spinning 24/7. CPU is undervolted and throttled. I want to get all the fans (except the PSU) under software control, including the chassis and hard drive cage fans.

Due to what I said above, it would have probably made sense to get a modern MicroATX board, but I didn't want to. 😀 I thought K8 Opterons were awesome when they came out and I wanted to play with one. The ability to dynamically throttle/undervolt the K8 helped convince me to try it.
The board is a Tyan S2882-D. About a year ago somebody on eBay was selling a bunch of these NOS at a good price. It's a very late manufacture (made in 2008 - this board came out more around ~2005). It had a later BIOS date than the newest public release BIOS, but that was misleading. It turns out the public release BIOS actually has better CPU support. I wasted a lot of time with confusing PowerNow/ACPI issues before realizing that.
I think these must have been ordered by a customer who wanted backups for their existing servers and never deployed them. That's maybe why they would have been ordered with an outdated BIOS. For some reason Tyan gave the outdated BIOS a newer date.

CPU is an Opteron OST280 2.4GHz dual core. Just using 1 because it's ample and duals would raise the idle power. I used WinXP with rmclock to do some undervolting experiments, and once I figured out safe settings, configured them in linux. It can idle with the fan (usually) stopped.
RAM is 2x 2GB DDR400 Reg ECC modules. It's plenty. It can definitely go up to 16GB using 2GB modules. 4GB modules might work, but there isn't much said about these by Tyan so it's uncertain. Either way it's still plenty of room to expand.
It's using a 66MHz Sil3124 SATA card because the onboard Sil3114 is connected to the slower 33MHz PCI bus. I'll be using this as a file server so I want the disk -> GbE performance to be as fast as possible. The onboard GbE and the SATA card are on different PCI-X buses.
I expect to start with 3x 2TB drives and a system drive. Long term, especially if I add more drives, I'm interested in SnapRAID.

It's running CentOS 6. As always, linux has been a slow battle but it has progressed. PowerNow throttling is fixed. Undervolting is done. Hard disks now spin down when idle. Minecraft is isolated using OpenVZ (I gave up on doing it with SELinux). Recently I've been working on temperature monitoring and software throttling of the fans (lm_sensors and so on).
I'd like the hard drive fans to be controlled by drive temperatures read through SMART. I haven't found a way to do this yet.

The onboard graphics is an ATI Rage XL. I thought this would be a good thing, because the Rage is one of the most common onboard graphics chips in the world. I thought it would be well supported, but apparently not. The Xorg devs decided it was obsolete and were seemingly proud of deciding to break it (along with many older video cards). I'm confused how they reasoned that a server OS doesn't need to support the nearly universal graphics chip of every server made in the mid-2000s. I don't think running linux on mid-2000s hardware is a rare pastime. Nobody at the distro or Xorg level bothered to add any detection, warnings, or automated workarounds for this. You just get a black screen for no apparent reason. It took some digging to understand the cause, and some screwing around to get past this problem, but it was possible by forcing an old version of Xorg and blocking it from updates.

This build has an interesting cooling issue. Due to undervolting there's a big difference in the CPU TDP between idle and high load.
The CPU fan is usually off when the CPU is idle. However, if hit with a load, it's shocking how quickly the core temperature can increase while the fan is spinning up. This needs work. If the fan ever failed, the CPU would be vapor in a few more seconds. I'm hoping there's a way to limit P-state transitions based on temperature.

This motherboard, like most multi-bus server boards, doesn't support S3 "Suspend to RAM". It's a bummer, but expected. I might set it to hibernate with wake-on-LAN, but that depends on what applications it runs.
Right now the idle power is about 67W (measuring with a Kill-A-Watt meter). 2 more drives need to be added (normally spun down), and I don't know whether I'll get complete control of the auxiliary case fans. Depending how things work out I expect the idle usage will land in the 65-70W range. 60W might be achievable somehow, but I think that's the lowest I could hope for with this motherboard. The old dual Coppermine setup has it beat on idle power by a good 20W.

SquallStrife wrote:

For years I had some heavily-specced system humming away 24/7 because I sort of felt I had to, for nerd cred or whatever. […]
Show full quote

For years I had some heavily-specced system humming away 24/7 because I sort of felt I had to, for nerd cred or whatever.

Last year though, I went low-power, and haven't regretted it.

My main server is an Intel Atom D525 based mini-ITX system with a 320GB 2.5"HDD, running Ubuntu 12.04 LTS. Also I have a QNAP TurboNAS with 4x3TB drives in RAID-5. About the heaviest task I use the server for is on-the-fly re-muxing of 720p MKV files for playback on my AppleTV, and it manages that alongside hum drum DHCP, DNS, VPN, Plex Media Server, etc no worries.

If this system stops working, I'll probably go to one of those Intel NUC boxes and save even more space and power!

I agree, power usage is definitely a concern for something that runs constantly. The system you use sounds efficient.

In the colder months, I run a space heater so the power use of a computer doesn't bother me (since it all dissipates as heat). But I'm almost thinking about having a separate low power server for the summer months. It might be awkward to transfer functions back and forth. Kind of a goofy idea but I have enough hardware laying around to try some things out.

I toyed with the idea of a computer as a heater, but you'd need 3 or 4 really high powered machines to have an appreciable effect.

A decent-ish sized column heater that runs off a wall socket is, what, 2000-2500W? You'd need quite the hefty computer to turn that much power into heat.

I guess it depends on your house construction too, if your room's insulation is good enough, then a small heat source like a computer could "trickle" heat your room throughout the day or night.

While a column heater is good, can you run servers off a column heater?

SquallStrife wrote:

I toyed with the idea of a computer as a heater, but you'd need 3 or 4 really high powered machines to have an appreciable effect.

A decent-ish sized column heater that runs off a wall socket is, what, 2000-2500W? You'd need quite the hefty computer to turn that much power into heat.

I guess it depends on your house construction too, if your room's insulation is good enough, then a small heat source like a computer could "trickle" heat your room throughout the day or night.

my dual 771 xeon can keep my garage about 5 degrees warmer than without. Then again I also do have 24 inches of insulation in the ceiling and the walls are brick & insulated.

Speaking of my 771. I'm going to be taking ti apart here soon to upgrade the cpu's and maybe install some more ram. not to mention clean it from top to bottom. I'll be sure to take pictures and post them here.

Here are our office servers and firewall in the data centre.

My home fileserver, builded from pieces found here and there: Pentium 4 @1800mhz on ASRock P4i65G, 2GB DDR400, 2x500gb IDE in striping, administered by FreeNAS:

My IBM eServer xSeries 345 dual Xeon @3200MHz, 2GB PC2100, 6x74gb SCSI 10k rpm:

mwdmeyer wrote:

Here are our office servers and firewall in the data centre.

Wow, I didn't realise ASUS made server boxes! 😁 😁

Yeah they were cheap! Both have worked well though, a bit low end, but stable.

Here is what they look like inside: http://www.vogonswiki.com/index.php/File:Asus_rs300-e6.jpg