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2 x 42A GPUs on a 65A 12V rail?

Discussion in 'NVIDIA' started by CyborgMouse, Jan 17, 2014.

  1. CyborgMouse New Member

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    Hi

    I want to upgrade to 2 GTX 780 Ti's in SLI which each requires at least a minimum 12V current rating of 42A. Currently I'm using a Corsair GS800(v1) which features a single 12V rail with 65A. Does that then mean my GS800 won't cut it? And does amps stack meaning I would need to upgrade to a PSU with a minimum 12V current rating of 84A?

    Sorry if it's a dumb question but I don't really know anything about power supplies or electricity in general.
     
  2. brandonwh64

    brandonwh64 Addicted to Bacon and StarCrunches!!!

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    in this situation I would not trust this PSU. When it comes to 2x600$+ GPU's I would just break down and spring for a better PSU.
     
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  3. Jack1n

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    In terms of power it will handle them,but if you have a sudden power shortage or if a your electrical grid is struck by lightning it might not protect your hardware the same way as a more expensive PSU.
     
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  4. satsol

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    800W is the minimum suggested for SLI, especially with two 780's, and if you're overclocking your the cards and even your cpu, you might have some issues. I would have to agree with brandonwh64 on this one, I would not trust that power supply to SLI big beefy cards like the 780's. The GS line are not quite meant for that level of performance. If you're sticking with Corsair I would look at the HX or AX line with 1000W minimum. However, if you want to save a little money, look at the EVGA SuperNova's, they are incredible psu's and just as good, if not better, than Corsair.
     
  5. RCoon

    RCoon Gaming Moderator Staff Member

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    You were on the right track until you said 1000w. 850w would be closer to the mark, 1000w is closer to triple sli/xfire territory...
     
  6. satsol

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    It's a little much, yes, however I lean on the side of having a little more headroom and more wattage than not. Even at 850w, I think you're cutting yourself a little short. I look at longevity and the fact the psu will loose efficiency over time, so in my opinion it's worth having the extra wattage, not to mention if you're buying two 780's, than what's another $30-40 to jump from a 850w to a 1000w and have piece of mind?

    OP: If you're really considering getting an AX1200i (which is overkill) from Corsair, take a look at the SuperNova 1300G2 from EVGA. Same quality, better warranty, and a lot cheaper.
     
  7. Frick

    Frick Fishfaced Nincompoop

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    So much this. I would trust the PSU, but if you can spend that money on GPU's you should really be able to spend more on the PSU as well.
     
  8. Tatty_One

    Tatty_One Super Moderator Staff Member

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    If I read a review like Guru 3D's and they recommended 800W as a minimum I would want more than 800W personally, of course 800W will do but once you factor in any GPU or CPU overclocking, well, lets just say I like a margin, if the OP does not overclock anything then go with the 800W.
     
  9. Jack1n

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    Are guys for real? 800W will not cause any issues even with 2x780ti,theres a guy here that runs a 690 on a 550w PSU.
     
  10. satsol

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    Just because a psu is 800w doesn't mean it's going to support your computer components the way that it should. There's far more to a psu than just total wattage. In the OP's case, he's going to be running very high-end graphics cards that require solid, stable power, and his psu isn't good enough in my opinion. Will it power them? Yes. Hell, a 750w would power them too. However, just because it can, doesn't always mean that it should. Having a cheap psu, or a psu being starved for power is not the kind of instability you want with a gaming rig.
     
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  11. brandonwh64

    brandonwh64 Addicted to Bacon and StarCrunches!!!

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    Yes 800W may support it but it would def give it a work out and probably lower the life expectancy by a huge margin and that can compromise your brand new 780Ti's
     
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  12. Frick

    Frick Fishfaced Nincompoop

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    [​IMG]

    @brandonwh64 He'll never reach full load with an 800w unit, it'll be fine even over time. Sure if he gets a 1200W unit he can power high power systems for a decade, but that might not be relevant.
     
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  13. The Von Matrices

    The Von Matrices

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    If he's using GPGPU programs, power consumption is going to be much higher than in a gaming load.
     
  14. brandonwh64

    brandonwh64 Addicted to Bacon and StarCrunches!!!

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    Sure that 556W but what does he have for the rest of his system? He only has 244W to spare to keep it healthy and a OCed CPU and multiple HD / fans can add up quick.
     
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  15. RCoon

    RCoon Gaming Moderator Staff Member

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    only
    ONLY
    ONLY?
     
  16. Mussels

    Mussels Moderprator Staff Member

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    those 42a suggestions are for the entire system, not just the graphics cards. i've gone and made a thread where people are comparing power consumption at the wall, and you'll be fine.


    do you have the worlds greatest PSU? no
    in an ideal world would you run that combination? no
    will it be fine, probably for a few years? yeah sure. just dont OC the system too hard.
     
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  17. BiggieShady

    BiggieShady

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    I see nothing wrong using only 50% of PSU's rated power at maximum load :D psu fan stays quiet, efficiency is at max and lower temps are good for the longevity
     
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  18. Aquinus

    Aquinus Resident Wat-man

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    That was my goal. My PSU barely warms up even when the entire machine is fully loaded. Less thermal expansion/contraction means better longevity.
     
    Last edited: Jan 17, 2014
  19. newtekie1

    newtekie1 Semi-Retired Folder

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    The GTX780Ti peaks at 269w, thats only 22A.

    The GS800v1 isn't a super great power supply, but it is a damn good one. I don't think it will have a problem with the SLI GTX780Ti's.
     
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  20. Tatty_One

    Tatty_One Super Moderator Staff Member

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    A GTX 690 at full load draws 373W, that's full system load so i would hope a 550W would power it, the test system though was not overclocked.
     
  21. Aquinus

    Aquinus Resident Wat-man

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    That definitely depends on the platform. My 3820 fully loaded will draw 350-watts easy by itself, forget loading the GPUs. We don't know what he has for a platform, so we really can't say how much it will draw.
     
  22. Bo$$

    Bo$$ Lab Extraordinaire

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    It's totally fine, Corsair is a good brand, no major risks to this, system wont pull more than 700W anyway. You'll be fine..... overclock your heart out. make sure you've got good airflow and your PSU can breathe and you'll be happy
     
  23. Tatty_One

    Tatty_One Super Moderator Staff Member

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    So you reckon you almost triple your TDP with that overclock? Damn, at 4.3 Gig my 930 pulls 214, and there was me think technology has moved on :)
     
  24. Aquinus

    Aquinus Resident Wat-man

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    At idle it draws a little over 200-watts. That's an increase of ~150-watts over idle. I wouldn't call it tripling the TDP since a sizeable chunk of that power is probably fans, hard drives, and the video cards at idle. Also consider for a moment that the PCI-E controller for me is on the CPU, for you it's on the motherboard. I'm also using 32 PCI-E lanes. So there are a lot of things that could impact my power usage; for example, multi-monitor consumes more GPU power at idle than a single display does.
     
  25. AsRock

    AsRock TPU addict

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    Yes for now it might be trust worthy but say in a year or 2 when the PSU has grown weaker..

    Better just to get one with some head room as it better to be safe than sorry even more so when it comes to PSU's.


    Not always true as they use cheap brands too.
     
    Last edited: Jan 17, 2014

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