Topic: anyone using an 850w PSU for 3x 7970? (Read 1188 times)

Thanks for the reply.

1. Im looking into this part.  Undervolting had not even occurred to me until Prelude brought it up.
2. It comes with enough for 2 cards.  1 (2 8 pin connectors) are on the main braid, the other 1 (other 2 8 pins) are a modular cable.  Corsair does sell extra cables and you can add 1 (2) more w/ an additional modular cable.
3. It is and it does.
4. Havent decided where it will be yet.  Right now Im thinking in the corner of my den.  It's an open space and usually the coolest room in the house.  My only concern here is noise since this is also the tv room, but we really only watch a couple hours on the weekends and rarely during the week.  If noise gets to be too loud I may look into water cooling though.

OP, a Corsair or Seasonic 850w is fine for 3x 7970 if:

1) you undervolt the cards, at least down to 1.08V or even better if you can get below.
2) the PSU has the required # of PCI-e connectors.
3) the PSU is single rail and provides 70A on the 12V line
4) the room is well ventilated and you take extra precaution in hotter days

Note that for 24/7 operation for months or even years, you shouldn't pull more than ~80% of the rated capacity, so 850w is really the minimum recommended.

what CPU are you using?  Do you know your power draw at the plug?  i know each card is different but i will gladly undervolt if i can still pull 750 per card.

No, over or under volting has no effect on hash rate whatsoever. The only thing that changes with voltage is: Stability, wear & tear (lower voltage = less wear) and heat (less heat with under volting, obviously). It can be a pain in the ass finding a card's lowest stable voltage, but it's totally worth it. The 3 cards that are running on my AX860i are running at 750KH/s each.

I don't "know" the answers.  I know what I've read.  I can apply this research and make an educated guess.  But people's real world experiences would be extremely helpful as well.  Hence the thread.  I am not doubting that a 1000w+ psu will do just fine for what I'm asking.  I'm not saying you're wrong in that.  I'm simply asking if anyone has had a different experience.


Case in point.  Do your hash rates suffer w/ the undervolting?  what kind of numbers are you looking at there?

I'm running 3 (undervolted) on an AX860i, no issues.

You know all the answers and still made a thread. 
I'll make it even more simple for you: Buy a kill a watt meter like many already have.

There, I edited the first post to more accurately reflect what I'm looking for.  Just because I'm a newbie on this forum doesnt mean I'm an idiot.  I know how to google search.  I've seen the same benchmarks you posted.  You post a link that supports your point, I post one that supports mine.  I cant go off a benchmark running the same card running on a high end board and 6 core (plus HT) X series CPU OCd to 1.5ghz over on water cooling and 4x the ram compared to my single core celeron and single stick.  That drops the wattage draw by at least 100w, probably more?  

http://hardocp.com/article/2011/11/14/intel_core_i73960x_sandy_bridge_e_processor_review/8#.UuGQ_YHn-c8
Here it shows a load power draw on that CPU OCd to 4.8 (same as the review i posted showing the 789 power draw for 3 cards) at 210 under load and 163 idle

http://www.xbitlabs.com/articles/cpu/display/celeron-g540-g440_8.html
The G440 does 15 at idle and 33 at load stock.  So if I go based on this my CPU alone shaves between 148-177w off that 789 figure.  I know how to google search.

Every time I see someone post a similar questions the response is "look at this review w/ a system totally unlike yours and draw your conclusions from that" or "Just get a 1000w+ psu and be done with it".  $200 for a 1000W psu vs $80 for my buddy's TX850M warrants a little bit of research.  Just because a review site did 1 test doesnt mean someone hasnt applied real world knowledge and made it work a different way.

You got the answer per your original post. This is yet another topic beat to death. Please use the Search feature.

1050W gold rated PSU and 3X7970 are working fine.
For 850W PSU -- 3x7950 or 2x7950+1x7970 is okay

Yeah but that test setup was using a 3960X OC'd to 4.2ghz and 4 sticks of ram.  My mobo/cpu/ram will be much less power hungry than that.

http://www.tweaktown.com/reviews/4883/sapphire_radeon_hd_7970_ghz_edition_vapor_x_3gb_overclocked_video_card_review/index17.html

This review shows a 3x crossfire setup w/ the same card pulls 789 at the wall using the same CPU OCd to 4.7 also w/ 16gb.  Assuming a lower power draw due to my celeron cpu and 1/4 of the ram, I would expect to come in under that.  I'm fairly certain a 900 could pull it off but the PSU i have a chance of getting is an 850.

Really, I'm wondering if anyone has any setups similar to this and if they were able to pull it off.

you need at least 1000 or 1250 to be safe.
You'll hear a boom soon ^^ if you keep on that

Use Search or Google, no need to post another thread on this.

http://www.tomshardware.com/reviews/radeon-hd-7970-ghz-edition-review-benchmark,3232-18.html

I have an Sapphire 7970 Vapor-X ghz edition w/ another on the way.  Im looking to upgrade the PSU to handle this plus leave room for 1 more down the road.  Im currently looking at an 850w psu (corsair TX850M), but im wondering if this will be enough for 3 cards mining?  Also, if I decide to OC the cards will it leave enough headroom?

Does anyone here have experience running 3 7970s on a PSUI under 1000w?