When browsing internet forums looking for questions that people ask about F@H, I often see people asking if it is worth folding on laptops (note that I am talking about normal, battery-life optimized laptops, not Alienware gaming laptops / desktop replacements). In general, the consensus from the community is that folding on laptops is a waste of time. Well, that is true from a raw performance perspective. Laptops, tablets, and other mobile devices are not the way to rise to the top of the Folding at Home leader boards. They’re just too slow, due to the reduced clock speeds and voltages employed to maximize battery life.
But wait, didn’t you say that low voltage is good for efficiency?
I did, in the last article. By undervolting and slightly underclocking the Phenom II X6 in a desktop computer, I was able to get close to 90 PPD/Watt while still doing an impressive twelve thousand PPD.
However, this raised the interesting question of what would happen if someone tried to fold on a computer that was optimized for low voltage, such as a laptop. Lets find out!
Dell Inspiron 1545
- Intel T9600 Core 2 Duo
- 8 GB DDR2 Ram
- 250 GB spinning disk style HDD (5400 RPM, slow as molasses)
- Intel Integrated HD Graphics (horrible for gaming, great for not using much extra electricity)
- LCD Off during test to reduce power
I did this test on my Dell Inspiron 1545, because it is what I had lying around. It’s an older laptop that originally shipped with a slow socket P Intel Pentium dual core. This 2.1 GHz chip was going to be so slow at folding that I decided to splurge and pick up a 2.8 GHz T9600 Core 2 Duo from Ebay for 25 bucks (can you believe this processor used to cost $400)? This high end laptop processor has the same 35 watt TDP as the Pentium it is replacing, but has 6 times the total cache. This is a dual core part that is roughly similar in architecture to the Q6600 I tested earlier, so one would expect the PPD and the efficiency to be close to the Q6600 when running on only 2 cores (albeit a bit higher due to the T9600’s higher clock speed). I didn’t bother doing a test with the old laptop processor, because it would have been pretty bad (same power consumption but much slower).
After upgrading the processor (rather easy on this model of laptop, since there is a rear access panel that lets you get at everything), I ran this test in Windows 7 using the V7 client. My computer picked up a nice A4 work unit and started munching away. I made sure to use my passkey to ensure I get the quick return bonus.
The Intel T9600 laptop processor produced slightly more PPD than the similar Q6600 desktop processor when running on 2 cores (2235 PPD vs 1960 PPD). This is a decent production rate for a dual core, but it pales in comparison to the 6000K PPD of the Q6600 running with all 4 cores, or newer processors such as the AMD 1100T (over 12K PPD).
However, from an efficiency standpoint, the T9600 Core2 Duo blows away the desktop Core2 Quad by a lot, as seen in the chart and graph below.
So, the people who say that laptops are slow are correct. Compared to all the crazy desktop processors out there, a little dual core in a laptop isn’t going to do very many points per day. Even modern quad cores laptops are fairly tame compared to their desktop brethren. However, the efficiency numbers tell a different story.
Because everything from the motherboard, video card, audio circuit, hard drive, and processor are optimized for low voltage, the total system power consumption was only 39 watts (with the lid closed). This meant that the 2235 PPD was enough to earn an efficiency score of 57.29 PPD/Watt. This number beats all of the efficiency numbers from the most similar desktop processor tested so far (Q6600), even when the Q6600 is using all four cores.
So, laptops can be efficient F@H computers, even though they are not good at raw PPD production. It should also be noted that during this experiment the little T9600 processor heated up to a whopping 67 degrees C. That’s really warm compared to the 40 degrees Celsius the Q6600 runs at in the desktop. Over time, that heat load would probably break my poor laptop
and give me an excuse to get that Alienware I’ve been wanting.