How To Reduce Computer Power consumption

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Marc Perkel's Guide to Making Computers use less Power

Several years ago I moved my servers over to Hurricane Electric. I remember my first night there. I was installing 7 servers. I had carefully planned the transition so that most people wouldn't have known the move happened. Everything went according to the plan and I went home and went to bed. Next morning I got up and everything was down. I had tripped the breaker on the power strip in the back of the cabinet. All of a sudden power was an issue.

My previous host had plenty of power. I had never really given that much thought to how much power I was pulling. All of a sudden power usage was an issue. Although the power strip tripped a little bit under the limit, I didn't realize that I was close to the limit. I was pulling between 12 and 14 amps! Wow! Had to get that down.

So I started doing some research into how to reduce my power consumption and over the years I've come up with quite a few tricks that not only cut my power usage, but increased computer performance at the same time. I've been very happy with the service I've had from Hurricane Electric and decided I'd write something up for other people who have their servers collocated in data centers. This is sort of a colo guide to reducing your power consumption. A lot of this is both easy and affordable so pay attention and you too can save power that would otherwise be wasted.

A little about me and what I'm doing

I have 2 companies. One is Computer Tyme Hosting a small web hosting company, and Junk Email Filter, my spam filtering company. Although I host a few big sites of interesting people, most of what I do is filter spam and host email. I also host a VoIP phone system and RBLs, black lists, white lists, and various spam related lists, and a few VPS servers for selected clients and friends.

Overview of how to save Electricity

In my quest to cut back on power usage I was surprised at how much I could save. There are several technologies I will get into starting with the most effective basics and then going on to the ones that help you squeeze out every last watt of power. The most effective methods involve replacing your power supplies with high efficiency (80Plus) power supplies. Then make sure you are running a modern kernel that has power savings built into the system. These are the two big tricks in cutting back on your usage.

Other tricks involve oversizing your computers. Many people don't realize that bigger computer can use less power than smaller ones. More ram, faster processors, bigger hard drives can help you use less electricity. I'll explain why that works. SSD (Solid State Drives) also cut power usage and increase performance. And then there's virtualization. Why add another box when you can create a new server in software?

Tools of the Trade

The first think you'll need is a way to measure your power usage so you can see what you are using and if you are making progress. There's a cool little device that you can buy almost anywhere called a KillOWatt meter. It usually sells for about $20 and will give you an accurate digital readout of how many amps you are pulling. You'll want to get one of these to monitor your progress.

First - the basics of power savings - power supplies and modern hardware and software

Old computer have old and inefficient power supplies. Typically they are 50% efficient or less. That means that for every watt you use it wastes a watt as heat. In a colo it's even worse because they have to use even more power to run air conditioning to get rid of the heat you are wasting. New power supplies can be bought that are 80% to 90% efficient. Look for the 80Plus seal.

If you like your computer but want to make it more efficient you can just buy the new power supply and just change it. If you have an older computer it might be more effective to just recycle it and get a new computer where you can take advantage of new power saving features. If you just change the power supply you'll be amazed at how much the current drops off. Same computer doing the same thing but now using less power.

If your computer has been running for several years you might be running an old kernel that doesn't support new power saving features of modern processors. Some CPUs will pull twice as much power using an old kernel as they do using a new kernel. This is assuming that your old hardware supports power savings. If it doesn't then it might be time to get a new computer. If you have an old computer it will eventually fail. Getting a new one resets the clock on the likelihood of old age failure and might save you a trip to the data center when your old piece of junk finally fries.

New kernels apply to all operating systems and processor brands. I personally am running Linux on AMD processors. But if you are using Intel and running BSD or Windows you too will see the power saving by upgrading to new hardware and new software. Doing these steps should cut your usage almost in half.

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