Replacing 2x7970 with 3x7950 - Need advice on 7950!

[endriuska]

Hey,

Right now I'm running 2x MSI 7970 and mining BTC, i get 680mhz per card, which is not bad, but taken that BTC diff is going up rapidly i decided to go with 3x7950 and mine LTC. Thus I paid $922 total for my 7970 which is way to much, so I will go back and exchange them for 3x7950.(same price). I have 3 choices:

1) http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=7542562&CatId=7387

2) http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=1967386&CatId=7387

3) http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=2555845&CatId=7387

Which one would you recommend?

I have 1000W PSU, rig will be kept in garage and I just received my 1x to 16x extenders so I will be able to have all the cards in the crate.

4) I have just 4gb of ram, will that be sufficient for 3x7950?

Thanks

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[pekv2]

Go with your option 1). The 11196-16-20G is basically the same as the 100352-2L which is found here http://www.newegg.com/Product/Product.aspx?Item=N82E16814202006 .

Dunno about the ram part.

Edit:
Note

Only one rebate per household for sapphire. So, even if you purchase three cards, you can only use one rebate.

[endriuska]

Thanks for the clarification! Any idea what should i get out of these? is 600khs a good enough? or should i try to squeeze out more?

[ryantc]

I know some of my friends can get 600 with MSI
and you need more ram.

my personal experience is:

I have three 7950 reference and I used to mine with CG and 4G ram
with MSI AB set to 980/1250 @ 1.063v I got just about 500 each card.

Last Friday I got some extra memory to put into the PC and now it has 7G of RAM
and I even lower the core, now MSI AB set to 970/1250 @ 1.063v

with CG I got 510 each card and with reaper I am getting 550 each card
so my conclusion is RAM does matter.

the only draw back about reaper is it doesn't support failover or stratum (I am sure you know you have to use stratum proxy to solve this) but failover pool, I haven't got a solution.

[endriuska]

Thanks again, just to reassure myself, I'm making the right decision by going with 3x7950 vs 2x7970?

Thanks

[pekv2]

Are you sure the msi is a reference? I don't see AMD printed above the pci express on the MSI. I know for sure 11196-16-20G & 100352-2L are references, as people stated they are and as these two have AMD printed above the pci express.

[ryantc]

Thanks again, just to reassure myself, I'm making the right decision by going with 3x7950 vs 2x7970?

Thanks

my calculation for your reference
if you push 7950 hard enough (eg MSI) you get 600 each, and 3*600=1800
but with two 7970 that means you need 900 each to make things equal (guess it's impossible)

In terms of money you paid for two 7970, that's really waaaaaaaaaaay to much
so I guess it's still worth the switch

Are you sure the msi is a reference? I don't see AMD printed above the pci express on the MSI. I know for sure 11196-16-20G & 100352-2L are references, as people stated they are and as these two have AMD printed above the pci express.

MSI? no they are not, my guess is any card with more than 1 fan/heatsink on it is no longer a reference.
maybe I write in a wrong logic, my experience is all about RAM, MSI mine @ 600 is another story