Thursday, December 26, 2013

LiteCoin Mining Part 3: Scaling Up

This post was supposed to be the finale to my LiteCoin mining series, but it really hasn't worked out.  I wanted to make more money LiteCoin Mining, so I ordered 4 ATI R9 290's and a 1200 Watt Power supply.  From eBay I got a 1-to-4 PCI Express 1x port multiplier, and four 1x to 16x PCI Express adapters.

All the kit came in and... It didn't work.  :(

I spent about a week troubleshooting it and determined that the PCI Express Port multiplier was defective.  I was able to resell two of the R9s locally for what I had in them.  The other two are mining away in my upstairs PC.  It's really convenient up there because I turned the AC off and they are keeping the bonus room warm.  I'd have to pay to heat that space anyway so it's a win.

Some things I learned from this:
1. My Gigabyte motherboard does not care for the 1x to 16x adapters.  The adapters are fine in my old eMachine.
2. Connecting Pin A1 to B17 on a 1x to 16x adapter will make some motherboards recognize it.  But not mine.
3. From the factory, ATI R9 290 video cards are limited at a maximum fan speed of 47%.  When the card gets hot it just slows down.
3a. You can get MASSIVE performance increases off these cards using MSI Afterburner and defining a new Fan speed Curve.
4. Setting any GPU tuning options in cgminer for the R9 290 causes the box to Blue Screen when you exit cgminer.
4a. This includes setting the fan speed, memory or engine clock, powertuning, etc.
4b. This does not happen if you do the GPU tuning in MSI afterburner.
4c. Windows 7 did not auto-reboot after the blue screen, Windows 8 does.
5. There are GPU tuning suggestions in the Scrypt Readme file included with CGminer.  They work.
6. CGminer throws an out-of error message when you try to mine using the defaults in cgminer.  Tuning the thread concurrency fixes this.
6a. The actual error is that it tries to use too much ram when compiling the OpenCL code for the GPU.  The solution for this is not more Ram.

I moved one of my old AMD Radeon HD 6790s into our living room PC.  It's given that PC a new life.  As I write this, my daughter is playing minecraft on it.  Fantastic!  From a Mining perspective, I've put a scheduled task on it to mine from Midnight until 6 a.m.  It's enough to cover the electricity cost of the machine. 

Since I started this project the price of Bitcoins and Litecoins has dropped in half.  I've seen this before, and I would urge everyone interested to buy into this lull.  They will come back, I'm sure of it.

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