PSU Question.. I've totally confused myself.

I did some searches and I found some pretty good explanations, but I'm still confused. I don't understand, Rails on PSU's.. I understand that each separate voltage has it's own rail and what not, but what I don't get is how it related to power for GPU's. What I've been trying to decide is if my HX850 (850 Watt, single 12v Rail @ 70Amps) would be enough to power two 580's..

Some have said with a quality PSU, running a single 12V rail at 70 amps (like mine) would be fine.. Others have answered that it's not enough and they def wouldn't trust it.

So how do rails and amps and total watts relate to each other and then GPU power?
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  1. volts * amps = watts. The 580 claims to draw 244 watts TDP, so 488w for 2 of them. You 12v rail claims to be 70w so 12x70=840w, which seems totally unrealistic for a 850w power supply, but is still probably enough to power 488w (and that's worst case) worth of video cards and the rest of your system.
  2. We have the same power supply, which I got because I read it was enough for two GTX480's. The GTX580 is supposed to draw less power than the 480, so it should be enough.

    "With 2-way SLI we noticed our power consumption for the cards peaked to roughly 719 Watts, that's quite something really, above two 480 actually which is strange to see with a card that supposedly has a lower TDP. Yet we also really need to mention that one of the boards used (engineering sample) had an older BIOS and that the power consumption on that board might be a tad higher as a result of it."

    They also had a major overclock, so I would say it depends on how stressed the rest of you system is. A GOOD 850 watt PSU should be enough.
  3. I think I'll give it a shot.. Can anything be damaged other than the PSU if in fact it can't handle it? I can deal with a fried PSU, but do I run the the risk of frying my rig?
  4. ct1615 said:
    care to explain why it would be unrealistic? maybe if you are used to junk PSU I could understand how its unrealistic. the PSU was tested by jonnyguru and passed its posted spec with flying colors.

    Didn't look it up, didn't know it was a corsair, and didn't know they even made power supplies with a single rail for everything, so I didn't think it was realistic to have only 10w for the 3.3 and 5v rails. My mistake.
  5. benski said:
    Didn't look it up, didn't know it was a corsair, and didn't know they even made power supplies with a single rail for everything, so I didn't think it was realistic to have only 10w for the 3.3 and 5v rails. My mistake.

    There is more than 10W for the 5 and 3.3 rails.
    Generally, there will be maximum amps for each rail and then an overall max wattage, so max wattage for 12V + max wattage for 5V + max wattage for 3.3V Rail might add up to 900+ watt, but the 'overall' is still limited to 850.
  6. I got my Corsair 850HX after reading a review that said it was the best power supply they had ever tested. It can easily pull more than 850 watts, so you should be fine with that one.
  7. It plays at 80 silver near to 80% should pull this through but is better to go with 80 bronze considering the drop after some time to get it at higher level 90% and above. There for this will make it without a problem:
  8. I didn't say it is not nice but the drop is near to 80% if you confortable with this go for it the in bronze the drop is near to 89% minimum.

    To be more specific is a very good psu it starts at 90% for some time this will help the capacitors to fill up fast but then it drops to 80% barely as silver you getting it? In the end with bronze you will get more than 90% at start and you will drop at 89% after some time. He speaks for 580 CF and also must have a motherboard with capacitors good enough.
  9. You gave me this in here i've seen barely 80% so it goes for silver.

    No i wrote if its silver then i go at 1200 watts psu in bronze 80 i go with 875
  10. PSU , "medal' rating is like the Olympics.
    Gold is the best
    Silver is 2nd best
    Bronze is 3rd best.
    Someone thinks that bronze is better than silver is wrong. I say this because the strange reasoning I'm hearing keeps coming back to that.
    Never mind, Corsair is one of the top name brands.
  11. Ok then we have a barely 80% the link that ct1615 gave a 89% Bronze the link i gave.
  12. Go in here and click the NEXT you will see everyting you gave me this link dam it!!

    finaly it drops to 80 they say in the test the drop after some time is the ISSUE.
  13. yes and it drops to 74% really nice you have nothing to worry about...
  14. Yes and finally drops to 74% in the link that i gave they selling it for bronze officially BUT the drop is 89% and the reason is the Japanese capacitor that hold stable at 105 C.

    The op in order to do it he needs a silver and is better to go for 1200watts silver to be sure also he needs the new japanese capacitors on the motherboard couse he speacks for 2 580 in CF.....
  15. ct1615 you have tired me you are giving the tests i will not sit over a 2% conversation in the bottom line even a GOLD PSU will not help him if he doesn’t have the same Japanese capacitor on board ok?

    I wrote if it silver ? go for 1200watts to BE SURE allright?

    and you gave this:

    then you found a thermaltake that gives this:

    so You can see clearly the thermaltake is more stable in the images the only reason for this ? Is the new capacitor allwrite?



    Bottom line you gave the links
  16. you found a thermaltake in here:

    and a Cosair in here:

    You gave me the links and the 775 is NOT the termaltake i suggested yet you can see the diffrence CLEAR.

    The reason that i tired is becouse you don't even see the images!!!

    Once again this the LINK you gave thermaltake:

    the other link you gave again Corsair:

    and make a favour see the images allright?

    the point is WHO is stable and who is NOT and this thermaltake in your link is NOT the THERMALTAKE I suggested and yet is better than your 850 in stability and this the ONLY reason that i took thermaltake you got it? all the other you posted is pure BS.
  17. What is this obsession with 1200 watt psu's ?
  18. He gave a corsair 850 and if you see the DROP in the images is HUGE in the and a thermaltake 775 witch is MORE stable in the images and he can't even see it. YET again is not the thermaltake i suggested is better than these 2.
  19. This thread is like a drug trip, when only one is in that trip.
  20. The corsair if you see the images does a HUGE drop and the Thermaltake does not or you pretend not to see it?

    I do care only about stability NOTHING else.

    In your test it get 85.1% NOT stable the thermaltake it gets 86.6% fully stable there is HUGE diffrence. IN my tests i can confirm these results this is WHY i stay in thermaltake and i suggest this brand.

    Do i made myself clear? You can suggest what you like i don't really care.

    Once again Thermaltake:
    Once again Corsair:

    All the other thinks they write about the price,the points, etc is pure BS (sorry about it) in the bottom line i get 86.6% Fully stable.

    And i'm telling you this baby in here:

    You will get 89% fully stable in startup maybe more but not under that. You got it?
  21. Deep breaths ct , take deep breaths. ;)
  22. I know this thread hasn't exactly degenerated into childish name calling yet, but I think the debate here is getting off topic. Before it goes any further down hill, I'm locking the thread.

    @ the OP,

    If you still don't have the answer you're looking for, please create another thread. Should that be necessary, I hope ct1615 and Giatrakis can keep their debate on topic without resorting to attacking each other.
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