<p>An answer can be found on bitcoin talk</p>

<p><a href="https://bitcointalk.org/index.php?topic=177855.msg1852355#msg1852355" rel="nofollow">https://bitcointalk.org/index.php?topic=177855.msg1852355#msg1852355</a></p>

<p>Quote from deepceleron on bitcoin talk</p>

<blockquote>
  <p>This is your GPU returning invalid hashes from it's kernel. This is
  because new drivers are crap for older cards.</p>
  
  <ul>
  <li><p>Uninstall AMD APP SDK</p></li>
  <li><p>Uninstall AMD Catalyst Install manager: choose "uninstall all software", make sure you have only a VGA driver after restart.</p></li>
  <li><p>Manually remove these files not removed by the installer; any other obvious ATI files with the same file date:<br>
  C:\Windows\System32\amdocl64.dll   C:\Windows\System32\amdoclcl64.dll 
  C:\Windows\System32\OpenCL.dll   C:\Windows\SysWOW64\amdocl.dll<br>
  C:\Windows\SysWOW64\amdoclcl.dll   C:\Windows\SysWOW64\OpenCL.dll</p></li>
  <li><p>Install just the Catalyst 11.11 driver package (no SDK is needed; the AMD APP runtime is included with driver)</p></li>
  <li><p>Mine just a bit slower on your 6870 than a 5830 would.</p></li>
  </ul>
  
  <p>Better:
  - use cgminer
  <strong>- set phatk worksize to 256 and underclock GPU RAM to 300MHz for best power efficiency and higher hashrate</strong></p>
</blockquote>

<p>The big thing to take away from this:
set phatk <strong>worksize to 256</strong> and <strong>underclock GPU RAM to 300MHz</strong> for best power efficiency and higher hashrate</p>

<p>A suggestion i can give you is that bitcointalk can be a great place to find the answer to a lot of off the wall questions related to bitcoin or any alt-coin. </p>

CC BY-SA 3.0
2013-06-22T05:17:31.980Z
2013-06-22T05:17:31.980Z
Joe White
<p>I just starting with mining today I have everything set up for slush pool on 
GUIMiner - v2012-12-03 .  I'm not sure what is wrong but this is what the console says</p>

<pre><code>2013-06-21 01:37:26: Listener for "GPU Miner" started
2013-06-21 01:37:28: Listener for "GPU Miner": stratum.bitcoin.cz:3333 21/06/2013 01:37:28, checking for stratum...
2013-06-21 01:37:28: Listener for "GPU Miner": stratum.bitcoin.cz:3333 21/06/2013 01:37:28, started OpenCL miner on platform 0, device 0 (Juniper)
2013-06-21 01:37:28: Listener for "GPU Miner": stratum.bitcoin.cz:3333 21/06/2013 01:37:28, no response to getwork, using as stratum
2013-06-21 01:37:39: Listener for "GPU Miner": stratum.bitcoin.cz:3333 21/06/2013 01:37:39, Verification failed, check hardware! (0:0:Juniper, a4627d39)
2013-06-21 01:37:51: Listener for "GPU Miner": stratum.bitcoin.cz:3333 21/06/2013 01:37:51, Verification failed, check hardware! (0:0:Juniper, 9fcd8ac2)
2013-06-21 01:37:52: Listener for "GPU Miner": stratum.bitcoin.cz:3333 21/06/2013 01:37:52, Verification failed, check hardware! (0:0:Juniper, 87fcf304)
2013-06-21 01:37:55: Listener for "GPU Miner": stratum.bitcoin.cz:3333 21/06/2013 01:37:55, Verification failed, check hardware! (0:0:Juniper, 5aa4b0f1)!
</code></pre>

<p>I also took a screenshot of the settings I have chosen <a href="https://i.sstatic.net/pwfvE.png" rel="nofollow noreferrer">here</a>.</p>

<getwork><verification><error>
GUI Miner no responses to getwork, and Verification failed
Hunter O'Rourke
# GUI Miner no responses to getwork, and Verification failed

(Asked by: username_0 on 2013-06-21)

I just starting with mining today I have everything set up for slush pool on
GUIMiner - v2012-12-03 . I'm not sure what is wrong but this is what the console says

```
2013-06-21 01:37:26: Listener for "GPU Miner" started
2013-06-21 01:37:28: Listener for "GPU Miner": stratum.bitcoin.cz:3333 21/06/2013 01:37:28, checking for stratum...
2013-06-21 01:37:28: Listener for "GPU Miner": stratum.bitcoin.cz:3333 21/06/2013 01:37:28, started OpenCL miner on platform 0, device 0 (Juniper)
2013-06-21 01:37:28: Listener for "GPU Miner": stratum.bitcoin.cz:3333 21/06/2013 01:37:28, no response to getwork, using as stratum
2013-06-21 01:37:39: Listener for "GPU Miner": stratum.bitcoin.cz:3333 21/06/2013 01:37:39, Verification failed, check hardware! (0:0:Juniper, a4627d39)
2013-06-21 01:37:51: Listener for "GPU Miner": stratum.bitcoin.cz:3333 21/06/2013 01:37:51, Verification failed, check hardware! (0:0:Juniper, 9fcd8ac2)
2013-06-21 01:37:52: Listener for "GPU Miner": stratum.bitcoin.cz:3333 21/06/2013 01:37:52, Verification failed, check hardware! (0:0:Juniper, 87fcf304)
2013-06-21 01:37:55: Listener for "GPU Miner": stratum.bitcoin.cz:3333 21/06/2013 01:37:55, Verification failed, check hardware! (0:0:Juniper, 5aa4b0f1)!

```

I also took a screenshot of the settings I have chosen [here](https://i.sstatic.net/pwfvE.png).

**Tags:** getwork, verification, error


---

## 1 answers

### Answer by username_1 on 2013-06-22. Score: 2

An answer can be found on bitcoin talk

<https://bitcointalk.org/index.php?topic=177855.msg1852355#msg1852355>

Quote from deepceleron on bitcoin talk

> This is your GPU returning invalid hashes from it's kernel. This is
> because new drivers are crap for older cards.
>
> * Uninstall AMD APP SDK
> * Uninstall AMD Catalyst Install manager: choose "uninstall all software", make sure you have only a VGA driver after restart.
> * Manually remove these files not removed by the installer; any other obvious ATI files with the same file date:  
>   C:\Windows\System32\amdocl64.dll C:\Windows\System32\amdoclcl64.dll
>   C:\Windows\System32\OpenCL.dll C:\Windows\SysWOW64\amdocl.dll  
>   C:\Windows\SysWOW64\amdoclcl.dll C:\Windows\SysWOW64\OpenCL.dll
> * Install just the Catalyst 11.11 driver package (no SDK is needed; the AMD APP runtime is included with driver)
> * Mine just a bit slower on your 6870 than a 5830 would.
>
> Better:
> - use cgminer
> **- set phatk worksize to 256 and underclock GPU RAM to 300MHz for best power efficiency and higher hashrate**

The big thing to take away from this:
set phatk **worksize to 256** and **underclock GPU RAM to 300MHz** for best power efficiency and higher hashrate

A suggestion i can give you is that bitcointalk can be a great place to find the answer to a lot of off the wall questions related to bitcoin or any alt-coin.


---

