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Buying a 2nd GTX280 today

Discussion in 'General Hardware' started by BarbaricSoul, Oct 7, 2009.

  1. BarbaricSoul

    BarbaricSoul

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    I'm sending off the money today to buy that GTX280 from trt740, and I'm wondering if my power supply will be plenty. If I had a corsair, seasonic, PC power and cooling, enermax or one of the other TOP OF THE LINE PSUs, I wouldn't be worried, but that isn't the case here. Is my cooler master real power pro enough to run the system in my specs with a 2nd GTX280 in SLI??

    Here's the product page for the PSU I have- http://www.coolermaster.com/product.php?product_id=2552
     
    Crunching for Team TPU
  2. BarbaricSoul

    BarbaricSoul

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    I would really appreciate some opinions. Last thing I want to do or can afford to do is fry my computer because my PSU can't handle the two GTX280's. I've found a 1k turbo cool PC power and cooling PSU for $115, do I need to buy that or not?
     
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  3. DaMulta

    DaMulta My stars went supernova

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    I bet you will be in the ok.
     
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  4. Tatty_One

    Tatty_One Senior Moderator Staff Member

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  5. BarbaricSoul

    BarbaricSoul

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    I hearing I'll either "be on the edge" or not able to run the 280's with my current PSU. I just sent a PM to the person with the $115 turbo cool 1k watt PSU. Thanks
     
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  6. Tatty_One

    Tatty_One Senior Moderator Staff Member

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    I think thats a very wise move, even NVidia state that for two 280's you will require more .....

    http://www.slizone.com/object/slizone_build_psu.html
     
  7. arroyo

    arroyo

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    Sell your GTX280 and go for HD5870. You would get:
    - less power usage
    - a lot more rendering power than 2xGTX280
    - most sexy card on market
    - I think cost of two GTX280 is more than a one HD5870. Isn't it?
     
  8. 1Kurgan1

    1Kurgan1 The Knife in your Back

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    Actually a 5870 will not be more powerful than 2x 280's. It will be more consistent since their won't be multiple GPU's. But a 5870 is a bit behind a GTX 295 and thats basically 2x 260's, and the 280 is quiet a bit faster than a 260.
     
  9. Lionheart

    Lionheart

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    gtx 295 is actually 2 gtx 275 on one pcb.
     
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  10. 1Kurgan1

    1Kurgan1 The Knife in your Back

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    Ah, wasn't exactly sure which one it was, but the 275 uses the 260 pcb, but better GPU's correct?
     
  11. Lionheart

    Lionheart

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    have you already bought the 2nd gtx280, like arroyo said, i would have done his idea.
     
  12. bogmali

    bogmali Moderator Staff Member

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    Contrary to what everyone has said so far..........I am running 2X GTX280 in my UD5 powered by the same exact PSU and they're both folding......Now the only thing that I'm not sure about is the SLI part (if it does draw more power from the PSU when they're linked). I also know for a fact that Mikeo47 ran 3 GTX260's on a 650W PSU so I would say yes;)
     
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  13. musek

    musek

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    Well, IMO you should be perfectly OK with your current PSU.
    Just check the review of ASUS MARS here, on TPU, especially the 'Power Consumption' page:

    [​IMG]

    As you know - Asus Mars IS the dual GTX 285. And if GTX 280 uses let's say... 20W less power, than you can add 40W to the result above and we are still under the 500W. And while I know, that CoolerMaster isn't a BeQuiet, Corsair or ENERMAX, still I'm quite convinced that it's not Codegen either :)D) and Real Power 750W should suit your needs perfectly well.

    PS. While I'd also go for the '5870' option i still wish you loads of fun and enjoyment with your GTX 280 SLI setup. 8)
     
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  14. BarbaricSoul

    BarbaricSoul

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    THX Bogmali, having to buy another PSU right now would really hurt my pocket. I do plan on getting a 1k PSU real soon (next paycheck).
     
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  15. BarbaricSoul

    BarbaricSoul

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    not really worried about power usage, my power bill is really low(under $75 a month)

    2 GTX280 are more powerful than the 5870

    matter of opinion on "sexest card on the market", personally I think the ASUS MARS GTX285 is the sexest card on the market.

    I already own one GTX280 and I'm getting the 2nd for about $180. Yeah, I could sell the 280's, buy a 5870, and possibly break even, and I might eventually. But for now, I'm gonna enjoy SLI.
     
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  16. 1Kurgan1

    1Kurgan1 The Knife in your Back

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    Remember, you also have an OC'd CPU and chipset to feed, a few other things like HDD's, but those don't require much power. I still think you will be in the clear, but not by too much.
     
  17. BarbaricSoul

    BarbaricSoul

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    Which is why while my current PSU might be enough, I'm still looking to upgrade my PSU, just not right this minute(unless I find a really killer deal and force myself to afford it)
     
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  18. Tatty_One

    Tatty_One Senior Moderator Staff Member

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    Well as I understand it, the TPU reviews are card power draw not system power draw so the equation is pretty simple, baring in mind that as mentioned, the Asus Mars will draw only slightly less power as it has the extra memory but its fairly safe to say that the 280 SLi setup may come in about 470W at full load (NO OVERCLOCKING), now add to that the fact that you have a quadcore CPU which at load WITHOUT overclocking will hit upto 135W TDP so lets call that 505W add to that all the other bits and bobs in your system and you are realistically talking probably 610W with no overclocking, OK, lets do some math......

    750W @ 80% efficiency rating equals continuous @ 600W

    Now remember, as i said thats at stock, now I may have added a little too much wattage in your peripherals but you need a safety margin and IMO you just dont have one.

    I dont doubt what some are saying that they know people running two 280's with the same or less but my point is, in the longer term they are pushing the PSU to it's max peak output which will result in the big bang or just plain old failure, all i can say is personally..... I wouldnt take that risk however if funds are the issue..... you may have little choice, whatever you decide just be careful!
     
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  19. extrasalty

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    Yes.
    People need to understand that most wattage is quoted at the wall(AC) which is understandable considering how cheap Kill-a-watt is. Power supplies are rated for DC Power. The difference is efficiency. Your 750W(DC) will hypothetically draw 937W(AC) at the wall if it was loaded fully and if it had 80% efficiency(common 80Plus PSU). Of course its not recommended to run it 24/7 at full capacity, so factor in 80% of max power rating as a good limit. So your system has to draw no more than 600W DC so you have 150 W slack.
    My GTX260 SLI, overclocked, running 2 GPU clients folding and 2 VM of 4 cores each so Hyperthreading uses its 30W(AC) and my system barely goes to 560W(AC), which is around 448W(DC) on my Corsair HX620 and around 72% of max power rating. Again this is 100% load on everything. Games barely load the cards compared to folding@home or furmark.
    It really depends on your usage, but if the components in you PSU are not up to par, it will probably have a shorter life.
     
    Last edited: Oct 8, 2009
  20. musek

    musek

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    Nicely said, extrasalty.

    And just for the record, this is the power usage of quite power-hungry PC from the Guru3D's Gigabyte Odin PSU review:

    Code:
    nForce 790i motherboard (has high power consumption) 
    Core 2 Quad QX 9770 Processor (overclocked to 3.6 GHz) 
    [B]2x GeForce GTX 295 primary (4 GPUs) [/B]
    3 GB Memory DDR3 @ 1600 MHz 
    Optical Drive x1 
    HDD x1
    [​IMG]

    IMO you are quite safe with 2 GPUs on CM 750W PSU.


    PS. I hope i'm not violating any forum rules by linking to other hardware site. If so - my apologies.
     
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  21. BarbaricSoul

    BarbaricSoul

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    Tatty, I 100% respect your knowledge and experience, and I am fully taking your advise. But also on the same count, I really can't afford a PSU upgrade til my next paycheck. Once I have the money, I will be buying a 1000 watt PSU, but until then, I'm gonna try running my CM 750. If I have one single issue, I'll pull the 2nd 280 until I get the new PSU(all it'll take is one crash). Also, I'll run my system at stock and try to under volt my CPU until I get the new PSU.
     
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  22. Tatty_One

    Tatty_One Senior Moderator Staff Member

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    I understand, as I said earlier, I am not disagreeing with anyone here, a 750W decent PSU will run them but again as I said, at full load overclocked in my opinion it is running "close to the wire" for long term use and personally I would not advise anyone to run close, anyone can quote reviews and sites, comparing 55nm GPU's with 65nm reviews is not completely accurate, I could tell you to pop over to VR Zone and look at their review of 280 in SLi with a quadcore at 3.6gig, a single HDD and a single optical and they were pulling 607W from the wall peak but that was with the GPU's at stock (I think), chances are you will be fine but at least if in the longer term it does go "BANG"..... I wont be the person you are pointing your finger at! :D

    Despite what we all have said in any case, W1zz's review that you posted above shows that he managed to draw 249W from a single 280, so double it, add 135W for a quadcore see what you have left for your peripherals and other hardware and fans etc........ those results would suggest that not all reviews are the same shall we say and may indicate contrary to what some have said..... especially when you see that W1zz managed to pull 320W from a single 295, double that to 660W which is more than the whole system consumption based on 2 GTX295's that someone mentioned earlier.
     
    Last edited: Oct 8, 2009
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  23. JrRacinFan

    JrRacinFan Served 5k and counting ...

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    Just read up on your OEM for that PSU, it could be a 70/30 respectively, Acbel or ChannelWell. Both have had bad pasts but are good OEMs.
     
  24. newtekie1

    newtekie1 Semi-Retired Folder

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    I'm pretty sure that is not how power supplies and efficiency work.

    The power supply is rated at 750w continuous DC power. The 80% efficiency means that the conversion from AC to DC is only 80% efficient(the rest goes to heat). So while the power supply is supplying 750w continuous DC power, it is drawing more AC from the wall. What the 80% efficiency tells us is: At full 750w load, the power supply will be sucking 935w from the wall.

    The important thing to note about his power supply though, is that the +12v is only rated for 648w continuous.

    Two GTX280s are going to peak about about 340w, based on W1z's review, the maximum they are going to pull during Furmark is !500w! but that will likely never occur in real world conditions, not even when folding.

    I am in completely agreement that, once you add in everything else, there is no buffer so your next move should be a bigger power supply. And until you do get a new power supply, don't run Furmark:D.
     
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  25. ShRoOmAlIsTiC

    ShRoOmAlIsTiC

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    i calculated your spec with the psu calcuator and it says you should be alright

    check it out here
    http://extreme.outervision.com/PSUEngine

    I know its not 100% correct but it should get you in the ball park.
     

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