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Hashrate Calculation Questions

Discussion in 'Mining' started by Starin, Apr 3, 2015.

  1. Starin

    Starin New Member

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    Hey guys. I am thinking to turn my desktop, ASUS Rog Tytan CG8480 into a rig. I really don't care about the ROI so my questions ar based on the effiency.

    I currently own a 4gb gtx660 card, which is actually old. Seeing 2k to 2.5k hashrates. I own a laptop with GTX760M and it gives around the same hash. Using ccminer.

    My motherboard does accept 4 more PCI-E 2.0 slots and after my research I concluded that GTX 750 Ti cards can work with 2.0 slots. My PSU is 750 watt corsair, so I don't think voltage would be a problem if I add 2 cards.

    The price of Nvidia GTX 750 is my country is around 170 dollars (THE OC ONE). What hashrate would I earn by adding 2 new 750 Ti OC's? My hash is 4000khs right now, what would be the sum with new cards? I use completely free electricity. Living at dorms. :p

    Please help me if 750 Ti's are my best choices. R290's are around 390 dollars here and my 2.0 slots wont probably support their watt needs.
     
  2. AlexMomo

    AlexMomo New Member

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    Numbers for X11 mining --> Nvidia GTX 750 TI = ~2700 kh/s

    So your total hashing power would be: (2x2700)+4000 = 9400 kh/s

    The GTX 750 TI is the best option for your setup due to power supply constraint.



    Cheers!
     
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  3. Starin

    Starin New Member

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    Hey man, thanks for the answer. 1 more question. Let's stay I installed GTX 750 Ti's to my motherboard. Can I have mine with only them and leave my GTX 660 for normal computer usage like playing games, ofcourse with out any delay or low FPS.
     
  4. AlexMomo

    AlexMomo New Member

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    You have a parameter in the mining software called <Intensity>.
    As an example, I have 2 Radeon 280X in my main PC.
    My main card (attached to my monitor) is mining at low intensity and I can watch HD videod and browse the web without any troubles. But playing game is not possible, sorry.
    My secondary card is fully dedicated to mining at full intensity and doesn't affect my system performance at all.

    Voilà!
     
  5. Sub-Ether

    Sub-Ether Well-known Member

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    I would not recommend running more than 2 GPU's from 1 power supply, have tried it myself and it blew up.
    Use a 2nd PSU to supply the 12 volt 6/8 pin molex's on the extra GPU's !
    Redundancy is always good, especially with mining.
     
  6. AlexMomo

    AlexMomo New Member

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    This is why the GTX 750 Ti is his best bet. They do not have messy 6/8 molex connectors, they are powered directly by the PCI Express lines and they consume less than 50 Watts each :)

    EDIT: After further researches it seems that the power consumption for X11mining is only 28 Watts per cards!
    WARNING: Some models of GTX 750 Ti have indeed a 6-pin PCI-Express connector. Choose your model wisely!
     
    #6 AlexMomo, Apr 4, 2015
    Last edited by a moderator: Apr 4, 2015
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  7. Sub-Ether

    Sub-Ether Well-known Member

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    Is it that low?! You make a good point, I was basing it on AMD R9 280X type spec, I should not make assumptions about Nividia being the same as I never use them :confused:

    I would add, that using normal PCB tracks to carry over 200 watts of power may not be ideal, but it might be designed to carry heavy loads, I don't know the board exactly so ...
     
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  8. AlexMomo

    AlexMomo New Member

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    It seems that 75W over lanes is acceptable for a x16 PCI Express graphic port. It`s the general spec for all 'consumer' boards (Asus,Gigabyte, AsRock, etc...)

    I do not own any Nvidia cards neither but I've read that the 'maxwell' architecture of Nvidia is really power savvy.
     
  9. Starin

    Starin New Member

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    Yeah, the watt usage is kinda why I prefered Nvidia cards atm. This would be my first time installing a second gpu to a motherboard. Would you recommend any specific guides or regular ones would be enough? Thank you guys for awesome responses btw.
     
  10. AlexMomo

    AlexMomo New Member

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    From there just add a card at a time, boot to confirm that the drivers are seeing your new card then shutdown your computer and add the other one. You should be golden!

    Good luck
     
  11. Wolf0

    Wolf0 Member

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    I can run three AMD cards off my SeaSonic 760W - it'll be fine. Either of my 1600W PSUs can easily take 5 GPUs.
     
  12. Sub-Ether

    Sub-Ether Well-known Member

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    Yer, I admit it was a cheap and cheerful PSU, but its still an awful lot of current coming out of a small box, high currents with thin wires and poor connections are points of failure
     
  13. 5kmi

    5kmi Member

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    From my experience over the past few years, you can run as many cards as your mobo can support as long as the the power supply is adequate. Buy a killawatt, worth it. I always leave a minimum of 20% overhead, ex: 750w psu, so my max draw is 600w. I have a couple of 5x7790 rigs that have been going for over 2 years now and the fatigue is just starting to show. In regards to powering low power cards, I'd actuallly recommend powering via pcie connectors rather than through the mobo. Yes the mobo was designed to handle it, but was it really designed to handle it 24x7x365? The first things to go are gpu fans, after that it's mobo failures. Those 2 year old rigs I mentioned have intermittent pci and usb bus failures. Can't fix it with software/drivers, so I chalk it up to mobo fatigue. What been used 24x7 for the last year or two on those machines? Pci and usb buses...Feed as little power through that mobo as possible and it will last much longer. Good luck with the rig!
     
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  14. qbit

    qbit New Member

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    ???? have you read any posts on bitcointalk.org? What you claim is plain wrong.
     
  15. Sub-Ether

    Sub-Ether Well-known Member

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    It was the power hungry AMD 6950's mining scrypt actually, as no doubt you know, X11 is way less power usage.
    At the time I was experimenting with a mining algo switching config, sha3 was also used and quite heaving on power but I didn't measure it.
    For a 1500 watt PSU you are obviously talking about fairly high end and expensive equipment but most small miners are not going to be spending $500 a shot on one single power supply are they?
     
  16. Wolf0

    Wolf0 Member

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    They're $300 - $400, and 3 - 4 GPUs will run fine on a 1200W, even on scrypt.
     
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  17. 5kmi

    5kmi Member

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    For the casual miner, who may need 800w to run 4-5 high end gpu's, it is typically cheaper to buy 2x500w psu's rather than a good 1000w unit. I've done this in the past as well. I still say the best way to avoid blowing a psu is to use a watt meter and always leave ~20% overhead.
     
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  18. qbit

    qbit New Member

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    well most decent 1000W PSUs are sub $150 and are "single-rail" delivering about 80A at 12V. Now it is not prudent to run them at full 80A, so you have probably 60A of power budget tu run your cards (rest of the system will use about 2-5A), which is probably enough to run 2 amd295X2 cards (slightly undervolted) with that supply. That's 37 MH/s X11 rig. That's more efficient than nvidia750Ti btw :)

    Or alternatively 4 stock amd280X cards. That's 27-29 MH/s rig.

    My 2¢: Don't mess with 2PSUs per rig if you really really know how this works. Take care.
     
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  19. splawik21

    splawik21 Grizzled Member
    Dash Core Team Foundation Member Dash Support Group Moderator

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    I had 2x750 PSU starting together the pin were connected and the rig was woring 24/24 for a year.... no issues ever.... meaby I was lucky? :)
    I got 3 280x there as with 4 cards one of them got lower hashrate and couldn`t bring all the same speed so I took one GPU out and it was cool for a long time till I sold all to buy the coins directly....