5 pci-e mobo rig / 5870 mining

[pewpew]

MOBO: ASRock 970 EXTREME4 AM3+ AMD 970 (3 pci-e x16 and 2 x1) http://www.newegg.com/Product/Product.aspx?Item=N82E16813157262
+ 2 x1->x16 risers http://cablesaurus.com/index.php?route=product/product&product_id=10

GPU: 5x 5870s overclocked

PSU: 2x XCLIO STABLEPOWER GOLD 750W http://www.newegg.com/Product/Product.aspx?Item=N82E16817189027
+ dual power supply cable http://www.frozencpu.com/products/11742/cpa-167a/ModRight_CableRight_Dual_Power_Supply_Adapter_Cable.html

CPU: AMD Sempron 145 http://www.newegg.com/Product/Product.aspx?Item=N82E16819103888
HDD: HITACHI HDS728040PLA320 40GB http://www.newegg.com/Product/Product.aspx?Item=N82E16822145527
RAM: CORSAIR XMS 4GB http://www.newegg.com/Product/Product.aspx?Item=N82E16820233132
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Each 5870 uses approx. 188W (+10% for overclock and +10% factor of safety) = 226W ea.
1 StablePower 750W for 3 x 226W = 678W
1 StablePower 750W for 2 x 226W (+200 for system power) = 652W
Despite not being commonly used, the Xclio StablePowers are actually top tier in terms of efficiency and stable output.

Entire rig will be AC cooled.

Any comments or suggestions on how stable this system will be for 24/7 mining (or 23/7) and what additional parts/cables will be needed are greatly appreciated! 

Topical discussion on 5870s very encouraged! For those running OC 5870s, what clock speed and wattage draw are your cards at? If you could give those numbers in percentage of original clock speed, MH/s, etc. that would be extremely helpful!

[rograz]

Depending on your electricity costs undervolting the cards might generate higher profits even tho you generate less MH/s, especially if you are going to AC cool them Oo? Also 5x 5870s undervolted to 0,95V can be run from a single 750 PSU without any problems so would save on your initial costs as well. Overcklocking hasn't really been a good option since back of the 10$/btc days unless you got cheap/free electricity.

I would use 1x flexible PCI-e extension cables in all slots and you might have to short the A1-B17 pins in some of the slots if they don't detect that cards.

[Littleshop]

Each 5870 uses approx. 188W (+10% for overclock and +10% factor of safety) = 226W ea.
1 StablePower 750W for 3 x 226W = 678W
1 StablePower 750W for 2 x 226W (+200 for system power) = 652W
Despite not being commonly used, the Xclio StablePowers are actually top tier in terms of efficiency and stable output.

Go with one PS. 

http://www.newegg.com/Product/Product.aspx?Item=N82E16817182063
Does not have to be this one, it is just an example of something that will give you headroom. 

Don't overclock too hard.  Your system will not use 200W for itself, it should be under 100W.  You should be able to get the system running at about 1100W and you will be more efficient. 

[silverbox]

That rosewill is like a freaking xmas tree

[pewpew]

Depending on your electricity costs undervolting the cards might generate higher profits even tho you generate less MH/s, especially if you are going to AC cool them Oo? Also 5x 5870s undervolted to 0,95V can be run from a single 750 PSU without any problems so would save on your initial costs as well. Overcklocking hasn't really been a good option since back of the 10$/btc days unless you got cheap/free electricity.

I would use 1x flexible PCI-e extension cables in all slots and you might have to short the A1-B17 pins in some of the slots if they don't detect that cards.

Any idea of how cheap the electricity needs to be in order for overclocking to be efficient? To rephrase the question: how many kWh does mining one bitcoin take on average and at what $/kWh cost does the electricity fees need to be in order to make that worthwhile (using 1 BTC = $5)?

Also, is having PCI-E extenders in all the slots for GPU cooling reasons or does it actually make things run smoother?

[Gomeler]

Depending on your electricity costs undervolting the cards might generate higher profits even tho you generate less MH/s, especially if you are going to AC cool them Oo? Also 5x 5870s undervolted to 0,95V can be run from a single 750 PSU without any problems so would save on your initial costs as well. Overcklocking hasn't really been a good option since back of the 10$/btc days unless you got cheap/free electricity.

I would use 1x flexible PCI-e extension cables in all slots and you might have to short the A1-B17 pins in some of the slots if they don't detect that cards.

Any idea of how cheap the electricity needs to be in order for overclocking to be efficient? To rephrase the question: how many kWh does mining one bitcoin take on average and at what $/kWh cost does the electricity fees need to be in order to make that worthwhile (using 1 BTC = $5)?

Also, is having PCI-E extenders in all the slots for GPU cooling reasons or does it actually make things run smoother?

Cooling reasons. On my 890FX-GD70s I run 2 cards on the board and 3 cards on risers. That way all the cards are spaced out nicely.

[silverbox]

Any idea of how cheap the electricity needs to be in order for overclocking to be efficient? To rephrase the question: how many kWh does mining one bitcoin take on average and at what $/kWh cost does the electricity fees need to be in order to make that worthwhile (using 1 BTC = $5)?

OC away if your profitable.  Anything less then 0.26USD/kwH and you should be profitable.

[Isepick]

That ASRock is an awesome mobo. Use this psu. You can easily get 4 of those 5870s on there, if you undervolt you can prolly get all 5. Or get 2 of them for the cost of that Rosewill and have a buttload more power. All 6 of the pcie connectors are 6+2 pin (with 5 5870s you'll need 5 of the 8 pin connectors), and the power rating on there is actually the continuous power, not the peak power like most advertise. It also has a 7 year warranty. I don't have 5 5870s, but I am running 2 5970s and a 5870 off the same board with this power supply, a 5970 with 3 5850s on another similar rig, and a 5970 with a 5870 and 2 5850s in a 3rd rig, all of which are that ASRock mobo and that psu.

[rograz]

OC away if your profitable.  Anything less then 0.26USD/kwH and you should be profitable.

I prefer my 4,8 GH/s@2,95mh/w (undervolted) vs 6,2GH/s@2,1MH/W (stock volt, OC) with my 0,18$ per kw/h earns me as much or slightly more with less heat and general hassle, unless my math fails me horribly :p

It's just a combination of undervolting and being able to run more cards/rig with the same psu without stressing the psu so it get's into low efficiency load area (keep them sub 75% of max pref).

[Beaflag VonRathburg]

PSU: http://www.newegg.com/Product/Product.aspx?Item=N82E16817814019 I have two of these and three cougar gx-1050s.

OC away if your profitable.  Anything less then 0.26USD/kwH and you should be profitable.

I prefer my 4,8 GH/s@2,95mh/w (undervolted) vs 6,2GH/s@2,1MH/W (stock volt, OC) with my 0,18$ per kw/h earns me as much or slightly more with less heat and general hassle, unless my math fails me horribly :p

It's just a combination of undervolting and being able to run more cards/rig with the same psu without stressing the psu so it get's into low efficiency load area (keep them sub 75% of max pref).

I punched some numbers and at $.125 / kw/hr I earn less than my rigs undeclocked. At .0625 It is more profitable to leave them at stock voltage. You need to get the rig up, running, and plugged into a kill-a-watt to get some base numbers. Then plug them into a profitability calculator and see how it works out for you.