HELP!: Problems mining on 3x 7950 Computer LTC Mining.

[GeekMan]

Okay, Z77 Extreme 3 with 3x Gigabyte 7950's, 8GB ram, 850W PSU.  Mining on Reaper v13b4

Some problems I am encountering mining LTC:

1. These cards run very hot so I cant run all 3 at 600 kH/s due to heat.  They auto-shutdown my computer once one of them reaches 100C.  What can be done about this?  Even with a huge 20" floor fan on top of them, they overheat.

2. I can get two of them to mine for a while, then my computer freezes and monitor goes black.  This is very annoying cause once I think they're all working fine, my computer freezes and they stop mining.

Here is my litecoin.conf:

protocol litecoin

worksize 256
vectors 1
aggression 20
threads_per_gpu 1
sharethreads 28
lookup_gap 2
gpu_thread_concurrency 21712

Im running 1015 core and 1350 mem.  I run on Windows 7 x64.  I just got these new cards and am disappointed.

If you whitelist me Mods, please move this thread to the proper section.

[shibaji]

Try this:

256 Worksize, vectors 1, Aggression 18, threads_per_gpu 1, sharethreads 32, lookup_gap 2, gpu_thread_concurrency 24576

[GeekMan]

Try this:

256 Worksize, vectors 1, Aggression 18, threads_per_gpu 1, sharethreads 32, lookup_gap 2, gpu_thread_concurrency 24576

I used those settings earlier and it crashed even more.  Im not sure if I should leave my core/mem at default or what?  How should I be managing this insane amount of heat?

[robble]

While you are probably on the right track with the overheating etc.. One other consideration could be the PSU.  I also have a high quality 850 but when I ordered 2 new video cards today I decided not to chance it and also ordered a 1250w PSU.

[Cereal]

How about getting some risers to place the cards wider apart?

Did you put them in a 'closed' case? maybe an more open setup would be good for your temps.

[rme]

Try another OS and another software

[Mylon]

Yea I'm running dual 7970's, your PSU is definitely an issue (got a 1k power here)

And beyond that, scale down on intensity / difficulty, till you get them to a stable tempature so they don't crash all over the place. (what I had to do with mine, they went 100+ instantly too, after scaling down, one kept stable at 95 degrees the other at 75... weird big ass difference I know...)

[GeekMan]

Okay, Looks like I had my rigs configured to go to sleep after 15 minutes!!!  Haha. 

The next problem is how to deal with the heat?  I can move my setup into a crate but, are there any solid risers/adapters so I can keep this in my case?

[vm1990]

id recommend taking it out of a case completly just to give you extra room to keep the cards apart and more air to play with. in a case alot of heat gets trapped and bakes card even more so when mining litecoins (pretty hard on GPUS) also keep an eye on the northbridge chip if you can hold your fingure on the heatsink its time for a little fan on it

[RauBan]

i've recently gotten myself a similar setup with 3x 7950s , but due to the pci-e extenders i ordered haven't arrived i can only put in 2 of them so far. as other people have said i believe the key is to use a very open case, i'm running 2 of them @ 620 kH/s and they're staying below 70 degrees C with about 50-60% fan speed.

[GeekMan]

Yeah, my case is running really hot.  I will need to move to a milk crate setup it looks like.  I just wish there was a way to still use the case and also use risers.

[dgagli1]

I got a 750w PSU.  Can I safely run 2 overclocked 1100 mHZ 7950 below 80C with this power supply?  I am currently running 1 overclocked pretty stable at 550 Hash and want to add another 7950.  Please advise if this power will be enough.  Also what would be the approximate total wattage output at these settings.

[GeekMan]

Should be fine.  I can run 3x 7950 non-oc'ed on a 750w.  (only other components are a SSD, 1 HDD, CPU)

[Tomatocage]

Undervolt them, dude. Running them at full factory voltage is a waste of power for mining and leads to high temps and high power draw.

[fastcrab]

Im running 1015 core and 1350 mem.  I run on Windows 7 x64.  I just got these new cards and am disappointed.

Have you thought about lowering the memory clock down?  Should save you a few watts.  Took me longer than I would rather admint to figure out how to get my new 7970 to run at CPU 1150 / Memory 375.

[GeekMan]

I dont think its possible to undervolt the Gigabyte cards?  They are overvolted stock at 1.25v I believe.

Would down-clocking the memory speed lower the hashrates on the cards?  What settings should I be using on my 7950's for clock/mem/voltage and still retain good hash rate and not burn down my house?

[fastcrab]

I dont think its possible to undervolt the Gigabyte cards?  They are overvolted stock at 1.25v I believe.

Would down-clocking the memory speed lower the hashrates on the cards?

For bitcoin mining you don't need the GPU memory speed.  Higher GPU Core Clock drives my hash rate higher.

If you are using scrypt for something like litecoin that is another story.

... oops!  you are going for LTC my bad!