I have never had a GPU for crunching PrimeGrid before.  What do I need to do to get my 1070 working for this challenge, besides:
1.  Finish current [link=mailto:F@H]F@H[/link] WU and then disable [link=mailto:F@H]F@H[/link] client
2.  Enable GPU crunching for the right project on the PG website
3.  Enable BOINC to use GPU
 
Anything else?  app_config tricks even?

This was a NZXT, will not buy another, Corsair so much better from my experiences...
The H80i is very old now...... how long did it last??

Punchy
I have never had a GPU for crunching PrimeGrid before.  What do I need to do to get my 1070 working for this challenge, besides:
1.  Finish current [link=mailto:F@H]F@H[/link] WU and then disable [link=mailto:F@H]F@H[/link] client
2.  Enable GPU crunching for the right project on the PG website
3.  Enable BOINC to use GPU
 
Anything else?  app_config tricks even?

I am also interested in any tricks.. This is my first GPU crunching challenge...

 
My settings that I am going with.
app_config.xml located in the \ProgramData\BOINC\projects\www.primegrid.com
 
<app_config>
<app>
  <name>ap26</name>
    <gpu_versions>
    <gpu_usage>1.0</gpu_usage>
    <cpu_usage>0.5</cpu_usage>
    </gpu_versions>
</app>
</app_config>

Punchy
I have never had a GPU for crunching PrimeGrid before.  What do I need to do to get my 1070 working for this challenge, besides:
1.  Finish current [link=mailto:F@H]F@H[/link] WU and then disable [link=mailto:F@H]F@H[/link] client
2.  Enable GPU crunching for the right project on the PG website
3.  Enable BOINC to use GPU
 
Anything else?  app_config tricks even?

That's it. No app_config tricks for a single gpu, a single wu uses 80 to 99% power on my 980ti. If running multiple gpu's in 1 rig you may need to run the cc_config to use all gpu's. Do a test and let us know the time to finish a wu. Also I'd leave the older drivers alone if you are going back to folding later. The wu says it uses .22 cpu but I don't see any increase in task man. You may want to back off a core for it though.
 
980ti takes 25 min per task.
 
Edit- or do what bcav says.

You can use the app config and run two WUs on one GPU. If you can do 2 WUs less than the time x2 to do one WU it is worth it.
Some times yes, sometimes no. It will load up the GPU and give off more heat.
Still having mild days here in NY, starting right now to not accept more WUS in WCG, I'll have to shut some down if I want to run GPUs
Gets way too hot in here.

26:12 for a single WU on a GTX 1070 SC.  I don't know if that's good or not?  I will try running 2 or 3 at a time, if I have any time before the challenge starts.

Punchy
26:12 for a single WU on a GTX 1070 SC.  I don't know if that's good or not?  I will try running 2 or 3 at a time, if I have any time before the challenge starts.

Can you post a link to your 26:12 time about that seems very long, like this http://www.primegrid.com/result.php?resultid=754634070
Sorry I corrected my settings  <gpu_usage>1.0</gpu_usage> if you change this the read 0.5 then it will run 2 Tasks Per GPU.
 
(My testing show this is best on my Rigs 980 or 1080 cards.
http://www.primegrid.com/results.php?userid=273570&offset=0&show_names=0&state=0&appid=11
1 Task Per GPU 1080 Run time 1,136.24 and Run time CPU 52.06
1 Task Per GPU   980 Run time 1,828.16 and Run time CPU 48.47
 
One Tasks Per GPU
 
<app_config>
<app>
  <name>ap26</name>
    <gpu_versions>
    <gpu_usage>1.0</gpu_usage>
    <cpu_usage>0.5</cpu_usage>
    </gpu_versions>
</app>
</app_config>
 
Two Tasks Per GPU
 
<app_config>
<app>
  <name>ap26</name>
    <gpu_versions>
    <gpu_usage>0.5</gpu_usage>
    <cpu_usage>0.5</cpu_usage>
    </gpu_versions>
</app>
</app_config>

Punchy
26:12 for a single WU on a GTX 1070 SC.  I don't know if that's good or not?  I will try running 2 or 3 at a time, if I have any time before the challenge starts.

Seems about right to me.  My 1070's take about 1460 seconds (~24 minutes) run time with about 60 sec of CPU.

This is the 26:12 WU http://www.primegrid.com/result.php?resultid=754922847