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Other => CPU/GPU Bitcoin mining hardware => Topic started by: The_JMiner on July 13, 2011, 04:31:43 AM



Title: New Rig 2nd GPU Question
Post by: The_JMiner on July 13, 2011, 04:31:43 AM
I just set up my new rig running.

Currently using 2 Sapphire Radeon HD 6750s

I am probably going to switch the cards later.  My operating system recognizes the 2nd card but Catalyst does not,
was I supposed to buy the Crossfire bridge as well???

(First time setting up twin GPUs)


Title: Re: New Rig 2nd GPU Question
Post by: gellimac on July 13, 2011, 07:12:07 AM
you have to make a VGA Dummy to simulate a screen on the second card or crossfire them


Title: Re: New Rig 2nd GPU Question
Post by: Jack of Diamonds on July 13, 2011, 10:16:36 AM
you have to make a VGA Dummy to simulate a screen on the second card or crossfire them

No, Catalyst 11.7 preview removes the need for dummy plugs or using any sort of plugs/CF bridges


Title: Re: New Rig 2nd GPU Question
Post by: gellimac on July 13, 2011, 11:22:26 AM
yes but 11.7 is in beta and cause many crashes (feedback i read) I suppose he is with 11.6


Title: Re: New Rig 2nd GPU Question
Post by: The_JMiner on July 13, 2011, 01:06:22 PM
yes but 11.7 is in beta and cause many crashes (feedback i read) I suppose he is with 11.6

Actually I have 11.2 and it says I was up to date. Are 11.6  & .7 in beta?
Should I get 11.6?

[edit] I installed 11.6 and I guess I will look into this dummy plug thing.


Title: Re: New Rig 2nd GPU Question
Post by: deslok on July 13, 2011, 01:14:19 PM
You only need a single resistor not a full VGA dummy


Title: Re: New Rig 2nd GPU Question
Post by: The_JMiner on July 13, 2011, 01:20:59 PM
Got it guys! I just installed a 2nd input from my monitor to the video card. Appreciate the help!


Title: Re: New Rig 2nd GPU Question
Post by: gellimac on July 13, 2011, 01:22:02 PM
the 11.6 is stable

to make a "free" VGA Dummy plug :

Quote
Here is how to make up a dummy plug for your card in about 30 seconds.

All you need are three 68 ohm resistors from RadioShack. They come in packs of 5 for a buck.

http://img293.imageshack.us/img293/8140/dvivgadummy001eh6.jpg
You will need the DVI-VGA adapter that ships with every GFX card, the resistors and a clipper. You could use scissors or a nail clipper, the wire is soft.

http://img291.imageshack.us/img291/5571/dvivgadummy002cu9.jpg
Bend one leg of the resistor around till it is parallel to the other then clip off the long leg so it is the same length as the bent leg.

http://img526.imageshack.us/img526/1516/dvivgadummy003ou0.jpg
The wire is just the right gauge to slide into the VGA plus securely.

http://img362.imageshack.us/img362/7225/dvivgadummy004mg7.jpg
Push it home. Note you want to bridge the top three pins on the right with the pins directly below one-to-one.. Hold the plug so the wide part is up top.

http://img362.imageshack.us/img362/197/dvivgadummy005ah4.jpg
Alternate the resistors so the leg of one is against the body of another to avoid shorting out the jumpers.

And that is all there is to it. Start Folding on your second GPU :D

From overclocker.net


Title: Re: New Rig 2nd GPU Question
Post by: deslok on July 13, 2011, 01:23:24 PM
i'm going to refer you to the complete thread
http://forum.bitcoin.org/index.php?topic=16816.0


Title: Re: New Rig 2nd GPU Question
Post by: Jack of Diamonds on July 13, 2011, 01:43:17 PM
yes but 11.7 is in beta and cause many crashes (feedback i read) I suppose he is with 11.6

I've run 11.7 on dozens of GPUs for many days now without any stability issues or fooling around with resistors or dummy plugs.

But if you want to take the hard route that's fine too, just saying dummy plugs are 100% useless now


Title: Re: New Rig 2nd GPU Question
Post by: gellimac on July 13, 2011, 01:57:46 PM
ok didn't know

to you know if we can bypass the gpu overclock limitation with 11.7?

Can i Reach 1000MHz/350MHz/1200mV with my 3 * Sapphire 5850 Xtreme?


Title: Re: New Rig 2nd GPU Question
Post by: Jack of Diamonds on July 13, 2011, 02:06:31 PM
It's card dependent, I have 1 5850 Xtreme that locks up at more than 880mhz regardless of voltage, then another that goes up to 960 @ 1.2V


Title: Re: New Rig 2nd GPU Question
Post by: gellimac on July 13, 2011, 02:21:57 PM
ok but for now i can reach 900MHz i want to reach more but can't because of bios limitation.

I want to know if (like with TRIXX) I can go over 900MHz?

You reach 960 MHz with a Sapphire 5850 Xtreme?


Title: Re: New Rig 2nd GPU Question
Post by: Jack of Diamonds on July 13, 2011, 03:03:30 PM
You can go over the limit by just modding the config file in Afterburner.

But voltage can be only modded by Trixx