FreedomBoxBlog

Building an energy efficient server

Rob van der Hoeven
Tue Mar 27 2012

Last week I finally built my first custom PC. It's very energy efficient, quiet and it can be used as a 24/7 server or as a general purpose PC.

The specs are:

Processor             : Intel G620 Dual core Pentium processor
Mainboard             : Intel Desktop Board DZ68DB
Memory                : 2 * 4GB PC3-10600 (DDR3-1333) (No Name)
Power supply          : Be quiet! Straight Power E9 400W
Hard-disk             : Western Digital Caviar Green WD5000AZDX, 500GB
Graphics              : Intel HD Graphics (integrated into the G620 processor)
Case                  : Recycled an old computer case.
DVD-writer            : None, I use an external USB drive if needed.

Hardware.

When I selected the system components I had the following main requirements:

To isolate my development work from the server-tasks, I want the server-tasks to run inside a virtual machine. The server-tasks are simple (personal web-server, email server, etc.) and do not need a very fast CPU (I am currently using ARM hardware for these tasks)

Because the machine is always on, its important that the system uses as little energy as possible. A one Watt device that runs for a year costs about 2 EUR in the Netherlands. Normal PC's like my old system easily consume 90 Watt or more when idle, which make them very expensive servers.

Both main usages of the system only occasionally stress the system so low energy consumption for the idle state is a main concern.

Here are some remarks on the components I selected.

Processor.

I selected an Intel G620 processor because its performance is more than enough for my simple tasks. I t has an nice integrated graphics core and low power consumption. With a price of only 54 EUR it's cheap too.

The specs mention a TDP of 65 Watt. My whole system never uses more than 60 Watt so this is a bit pessimistic. I think a TDP of 35 Watt like the special energy efficient G620T version is more realistic. When compared with the G620T the G620 only uses one or two Watt more.

Mainboard.

Finding the right mainboard was a bit tricky. Power consumption varies quit a bit between different products. Even when idle the difference in power consumption can be over 10 Watt! A very nice comparison of 21 mainboards can be found here. From this comparison you can see that the Intel DZ68DB mainboard I selected does very well.

Power supply.

Here I had two requirements. High efficiency and low noise. These qualities are both present in the selected Be quiet! Straight Power E9 400W. This power supply has an 80Plus gold certification, which guaranties an efficiency of 90% or more. For cooling an 135mm SilentWings fan is used resulting in an extremely low noise level of under 15 dB(A) at full load. With a price of about 70 EUR this power supply is twice the price of a standard power supply. When I look at the specs and build quality I find this very good value for money.

Memory.

Not much to say. I bought 8GB just to be able to compile very large programs and run the VM's

Harddisk.

I bought an energy efficient Western Digital Caviar Green WD5000AZDX, 500GB. This HD is fast and almost silent.

Graphics.

The integrated graphics core of the G620 processor is more than capable for any graphics task other than gaming. Video decoding is pretty good. I even managed to play the “killa sampla” with only a small distortion in the first two seconds of the clip.

Software.

At the moment i'm running the testing version (Wheezy) of Debian GNU/Linux on the system. Quite a nice experience, everything worked out of the box and no proprietary drivers needed to be installed.

I only needed to make some small adjustments to the kernel settings in order to lower the power consumption. It turns out that the 3.x kernels have support for the power saving features of the integrated graphics core of the G620 processor, but these features are disabled by default. To turn the features on you have to edit the grub boot configuration as follows:

Edit:

/etc/default/grub

Find the line:

GRUB_CMDLINE_LINUX=""

Change it to:

GRUB_CMDLINE_LINUX="i915.i915_enable_rc6=1 i915.i915_enable_fbc=1 i915.lvds_downclock=1"

Save this configuration and activate the settings with the command:

update-grub2

After restarting the system consumes 7 Watt less power...