Use of 4x HD6990 cards

[d3m0n1q_733rz]

Hello, I am looking at building a rig with 4x HD6990 cards in it and I wanted to know if I would be required to connect each card to a display before their GPUs would be activated for mining.  I know in past calculation programs, it was required for a display or null to be connected to at least one port of each card before the GPUs would do any work; has this changed with OpenCL or do I need to invest in null devices?

Thanks!

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[muyoso]

You could take a single monitor and plug it into the first card, start the miner and then plug it into the second card and start that miner, etc.  But you would have to do that each time you restarted the miners.  Would save a bit of money though.

[trentzb]

On Windows I believe it is necessary to connect a monitor or dummy plug to each card. On Linux it is not necessary.

[phillipsjk]

Apparently the "dummy plug" can consist of a strategicly placed 87 Ohm resistor (one of the color channels (say green) -> ground))

[jwzguy]

Dummy plug didn't work for me. Also, although I bought an MSI 890FXGD70 (quad xfire supposedly), installing more than 3 cards gave errors with MSI Afterburner. Not worth it, just have to put the 4th card into another machine.

[arc45]

On Windows I believe it is necessary to connect a monitor or dummy plug to each card. On Linux it is not necessary.

Thanks for saying that.  I was wondering why my pc couldn't see the 5870.

[galtbit]

hmm..

[xide]

dummy plugin depends of driver version...