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.