Overclocking The HP Touchpad For Cryptocurrency

I mention in my September 9th post that I was able to get a Bitcoin/Litecoin mining daemon (cpuminer) running scrypt calculations on the HP Touchpad.

Because a device like that is one of the worst possible things you could use to generate cryptocurrency, I’ve left it running as a dedicated Litecoin mining machine since then. It’s generated nearly a quarter of a cent worth of imaginary money in the past week.

This is a Touchpad with the stock kernel at 1.2 GHz:

[2013-09-09 01:37:27] thread 0: 43849 hashes, 0.74 khash/s
[2013-09-09 01:37:46] thread 1: 46406 hashes, 0.77 khash/s
[2013-09-09 01:38:28] thread 0: 44242 hashes, 0.74 khash/s
[2013-09-09 01:38:46] thread 1: 46395 hashes, 0.77 khash/s
[2013-09-09 01:41:33] thread 1: 23011 hashes, 0.38 khash/s
[2013-09-09 01:41:39] thread 0: 25365 hashes, 0.38 khash/s

The drop to half rate is because the CPU is throttled to half speed when the device goes idle. I’ve heard that you can overclock a Touchpad, but have never looked into it because it’s been fast enough for me.

Here’s a blog post that details how to tweak your Touchpad for performance:

http://jasonnash.com/2011/09/05/tweaking-that-new-hp-touchpad-you-just-got/

This is the Touchpad with the stock webOS Internals “uberkernel” (no settings changed):

[2013-09-09 03:23:58] thread 0: 13388 hashes, 0.30 khash/s
[2013-09-09 03:23:58] thread 1: 13363 hashes, 0.30 khash/s
[2013-09-09 03:25:27] thread 1: 18193 hashes, 0.20 khash/s
[2013-09-09 03:25:27] thread 0: 18232 hashes, 0.20 khash/s
[2013-09-09 03:26:00] thread 1: 12187 hashes, 0.37 khash/s
[2013-09-09 03:26:00] thread 0: 12208 hashes, 0.37 khash/s

That’s worrisome, shouldn’t it be faster? It seems that the stock install optimizes for power savings rather than speed.

With the UberKernel set to OnDemandTcl 1512 (1.512 GHz):

[2013-09-09 03:31:22] thread 1: 57473 hashes, 0.95 khash/s
[2013-09-09 03:31:23] thread 0: 50465 hashes, 0.87 khash/s
[2013-09-09 03:32:20] thread 1: 56374 hashes, 0.98 khash/s
[2013-09-09 03:32:20] thread 0: 51996 hashes, 0.91 khash/s

That’s right, 1.8 khash per second! Blazing fast! You may also notice that it’s bursting as high as 0.98 khash per core…

OK, here goes. I’m probably going to melt my pad, but 1 khash per CPU is within my reach. Could you imagine a 2 khash tablet? Dang, that’d be nosebleed-worthy.

[2013-09-09 03:45:44] thread 1: 67142 hashes, 1.11 khash/s
[2013-09-09 03:46:42] thread 0: 62675 hashes, 1.06 khash/s
[2013-09-09 03:46:43] thread 1: 66417 hashes, 1.11 khash/s
[2013-09-09 03:47:17] thread 0: 37319 hashes, 1.06 khash/s
[2013-09-09 03:47:17] accepted: 2/2 (100.00%), 2.17 khash/s (yay!!!)

Yay indeed. I did it! A kilohash per core per second! 2150 hashes! Victory!

I also tried mining Bitcoin with cpuminer on the HP Touchpad using SHA256 calculations, and the power was considerable there, too:

[2013-09-10 01:20:15] thread 0: 40506764 hashes, 762.24 khash/s
[2013-09-10 01:20:16] thread 1: 47714636 hashes, 789.13 khash/s
[2013-09-10 01:20:58] thread 1: 33848421 hashes, 800.30 khash/s
[2013-09-10 01:20:58] thread 0: 32404380 hashes, 759.41 khash/s

That’s right, more than a three quarters of a megahash! That’s a BTC generating /machine/.

I don’t think this is something I should try to sustain, though. The CPU made it as high as 32 degrees C, in a room that was 24 degrees C at the time.

I’m going to be rich! Wait, you mean I only earned a thousandth of a cent during this experiment? Oh well, there goes my dream of a Touchpad mining farm…. creating a penny worth of imaginary money for each dollar of electricity is something you probably can’t make up on volume.

2 Comments

  • Sal says:

    Forgive my noobness here, but I have access to a number of touchpads that are laying around….I am VERY new to bitcoin….but “in theory”….if these could be placed in a very cool environment…powered by solar….what are the chances of turning a profit?

    • Xangis says:

      There is absolutely zero chance of turning a profit. The trouble is that a Touchpad, which runs at about 5 watts with the screen off, has a hash rate that is about 1/1000th that of a pair of 2.5 watt ASIC miners that can be purchased for $25 (or less) each. Even though the payback rate is bad, you’ll make more money selling the solar energy back to the power company. You would be lucky to earn a penny a month running mining on a Touchpad. I just did it as in intellectual exercise in doing dumb things. 😛

      It’s more common to use something like a Raspberry Pi as the controller for a bank of ASIC miners. It keeps your power consumption down while being able to control high hashrate devices.

      Something to keep in mind — over the past month the hash rate of the bitcoin network has increased by around 50%, and as more ASIC hardware is coming to market, that rate of increase will only accelerate. Unless you’re the one selling the shovels, there’s no real money to be made in mining. Trading the currency has some better opportunities, just like trading in real currency (FOREX).