Monthly Archives: March 2017

I Got a New Watt Meter!


No, really…I have been without a watt meter for over a year.  This is a tragic thing for an engineer.  What happened is that I lent my trusty P3 Kill-A-Watt Meter to a co-worker, who then quit and moved.  He did kindly pay me for it on his last day, when he realized he’d never given it back, so there are no hard feelings…

Well, with the restart of this blog, it was obviously time to pickup a new watt meter.  I decided to buy the Belkin Conserve meter based on the fact that the display is separate from the wall outlet.  This makes it much easier to read…no more bending over to peer behind the desk.

I also picked up a new P3 Kill-A-Watt meter, because I missed my old one so dearly.  Also, this is the watt meter that all other watt meters are judged by!  See my previous article here:

Fun with Watt Meters

Both of these power meters cost about $25.  The P3 is loaded with many more features, such as monitoring phantom power, real power, line voltage, etc, but for the purpose of this blog all I looked at is the basic power monitoring function.

Of course I then needed to test these two meters against each other.  Since the P3 is what I had been using, I wanted to make sure the Belkin reports similar wattage results for a given load. As with any power electronics, it is important to test the circuitry and different load levels to make sure results are consistent with draw.  So, I used three household items to benchmark these two watt meters against each other.  The items I selected are constant-load items, which means that the power usage doesn’t jump around much during the test.  This makes things comparable.  Using a computer here would have been difficult, because computer power consumption is all over the place depending on what the darn thing is thinking about in the background.

Test 1: Yamaha Piano

The trusty old Yamaha piano was used to test how these watt meters report power for a low-load condition.  I set the piano playing one of the generic, annoying songs it came pre-programmed with (all of these songs are now annoying since our 2-year old plays them constantly on repeat).  Anyway, here the new Belkin meter showed a slightly higher power consumption than the P3 (8.8 vs 8.2 watts).  For these low power levels, the discrepancy was about 7%, which isn’t a great number.  This would be a bit disconcerting if we were intending to measure the power consumption of low-draw devices.  Thankfully, computers typically draw 100 watts or more.

Test 2: Humidifier 


Our bedroom humidifier was used as a representative medium-load device.  It draws nominally 40 watts, and some ultra-efficient desktops and many small laptops will have a power consumption in this range.  Here, the Belkin meter reported a slightly lower power consumption than the P3 (33.7 vs 35.2 watts).  The delta between meters in this case is about 4 percent, which is better than the low-load test but still annoying.  Unfortunately, I didn’t have any convienant constant-load items in the 200-300 watt range, so the next test really ramps up the power.

Test 3: Space Heater

The space heater was used to represent a high-load. With a power draw near 900 watts, this would represent a monster desktop with multiple graphics cards. The Belkin reported two less watts consumed than the P3 (874 vs 876 watts).  Here, the percent difference is only 0.2%.  This is a good number.


For the expected power consumption of desktop computers in the 100-300 watt range, the Belkin and P3 meter will probably be within 2% of each other.  The more power consumed, the less the % difference between these two meters.  So, I think power readings taken with either meter should be comparable enough to each other.  Still, I will likely make all computer measurements with the Belkin, for the aforementioned reasons of ease of viewing.  With this meter properly positioned, you can geek out while gaming, folding, or playing the piano.  Not bad for 25 bucks, right?



Where I’ve Been

So two years later and I’m finally posting.  Phew!  It was hard enough just finding time to write this.  The short of it is that life happened, and I just didn’t have the time to keep going with the blog.  Actually, I stopped folding as well, due to very high electricity costs in Connecticut (averaging about 18 cents per kWh, which is insane).

But now that our second child is a little less cranky, and now that we are out of that tiny apartment (we bought a house), I think I’m finally feeling settled enough to resume this blog.

Consider this a second kick-off.

As some of you have mentioned, the real computational power these days is in graphics cards. Actually, even when I was writing regularly two years ago, GPUs were the ticket to massive PPD and better efficiency.  The reason I wasn’t talking about them was because I felt it was important to start where F@H started and discuss CPUs.

Over the years I have folded on many graphics cards.  The list, as I recall it, goes as follows:

  • NVidia Geforce 8400 GS (PCI)
  • Nvidia Geforce 240 GT
  • AMD Radeon 3870
  • AMD Radeon 4870
  • AMD Radeon 5870
  • NVidia Geforce 460 GTX
  • AMD Radeon 7970 HD

You’re probably looking at this list and thinking, wow, those are some old GPU’s.  Well you’re right!  Originally I was going to write a blog post about each one of them, and include tuning info and lots of pictures.  Since I don’t have any of those GPUs anymore, with the exception of the 7970, that’s not going to happen.  Oh well…

The takeaway of all those articles though would have been this:  any of those GPUs (with the exception of the wimpy 8400) offered better performance and efficiency than the contemporary CPUs in the similar price range.  The higher end graphics cards (7970) offer significantly more points per day performance, and although power consumption is typically higher than a CPU-only folding rig, the performance  gains are exponential and efficiency is greater.  This is because the massively parallel architecture of today’s graphics cards offers tremendous floating point computational capability compared to central processors.

Going forward, I plan to take a look at new graphics cards (think 2017 vintage).  These cards generate anywhere from 100K PPD up to well over a million PPD.  But first I need to describe my new power meter, which will be the focus of the next post.