Does anybody compared mining on 1 GPU and 2 GPUs?

[darklord]

Like in subject... Can anybody share any numbers? Does 2 GPUs really increase mining by x2?

[coinspoolco]

Yeah sure it does increase by 2x. The cgminer uses 100% of both card, not like games where you can see only a small % of increase with additional cards.

[mastero9017]

Like in subject... Can anybody share any numbers? Does 2 GPUs really increase mining by x2?

Yes, also with cudaminer.

[batoelrob]

I cross-fired two different cards, one gives 650 KH and the other 400KH, functionates good.

[cgayle]

Most probably, the estimated gpu performance will be achieved with any number of gpus you add.

You need to take care to power it proerply with proper psu and cables.

[superresistant]

Well, not exactly.
First you need exactly the same GPU (brand) to compare.
Then, depending on the excess of heat due to a bad position in the RIG, the GPU with less air flow could be badly cooled causing a slower hash rate.

[Jaerky]

I wanted to try that out, but my case is too small. Especially since I just installed a GTX 670. I bought that before I ever knew about the hashrates as it replaced my Radeon 7850.

Is it worth it to get 2 cards? Do they double the efficiency of mining? I'm thinking about getting a new rig just for mining. Not sure if I should invest the money now or wait for the new specialized mining machines coming out for the Scrypt coins.

[bojecht]

I cross-fired two different cards, one gives 650 KH and the other 400KH, functionates good.

Do not put them in crossfire, it is slowing them down

[infinitybo]

@Darklord It's a nice question however it does increase by two.