Mining with multiple cards - understanding question

[nookiegirl]

Hi everybody,

I have already followed the threads some time now and I am missing some understanding concerning the mining with multiple graphic cards.

If I setup a mining rig with e.g. 4 cards, do I have to combine them into one card (via SLI for example) or can I mine with each card separately? Also, if both is possible, which method is likely to generate more Mh/s?

Thank you

[charybdis]

Download a miner and start mining, and it will become more clear how it works. I don't think SLI makes any difference - just as long as the miner can use all of the cards.

If you're using SLI you must have an Nvidia card. Nvidia cards don't typically mine as quickly as ATI cards, you should check this out if you haven't already: https://en.bitcoin.it/wiki/Mining_hardware_comparison#Nvidia

[nookiegirl]

@charybdis: thanks for the reply.
I only used the term SLI, because I don't know the equivalent for ATI cards.

Currently I cannot try this out, because I do not own a rig yet. So this is only for my understanding to find out what is more common to use. Can the mining software handle 4 cards at the same time via a one running instance or do I have to start 4 instances?

[DaCash]

I am sure cgminer could handle all cards with only one instance. And be sure to use latest version (2.11.4 as of now)

[nookiegirl]

So If I have 4 cards, each doing 500Mh/s and I start the instance with all 4 cards, can I expect to have 2000Mh/s?
If I combine those 4 cards via crossfire (i have googled the term now) and start e.g. cgminer will I also get those 2000Mh/s or rather less/more?

Sorry for bugging

[avulhop]

I was wondering something very similar myself. I have a 7850 in the mail (I mostly intended to game with it and mine on the side while idle), but I saw someone had a used 5870 for sale super cheap on craigslist. I know they don't Crossfire well/at all, but I wondered if they could be run independently if I just plugged it into a spare PCIe slot as a dedicated mining card.

[Aahzman]

my understanding is that crossfire doesn't provide any benefit when mining, but it doesn't hurt your hashrate either...

[nookiegirl]

So if you use cgminer for example, how do you specify to use 4 cards in one instance?
And how do you specify different options for each card?