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Topic: So what is the consensus on how many 7970's can run on one rig ? (Read 2560 times)

full member
Activity: 812
Merit: 108
I just smoked a silverstone strider 1500w running 4 7970's, not overvolted, with a 2500k... Last ShitterStone product I'll buy.

Thats what I'm running :/

Though mine has shown no signs of problems at all

What were you running your 7970s at? What was the draw at the wall? ~950w?

Never put a meter on it but I would assume around 1100 range.  Hopefully the RMA process goes smoothly.  I've heard lots of people have had great luck with them, I must have just gotten a bad one.  At first it would disable 2 vid cards, I would try to re-enable them and mine again and it would lock up and shut down, then I was mining on 2 cards till my replacement psu showed up, but that only lasted 12 hours or so.  If I didn't have a spare 300 bucks laying around I would be stuck watching the difficulty climb, not mining a damn thing lol.
member
Activity: 65
Merit: 10
I just smoked a silverstone strider 1500w running 4 7970's, not overvolted, with a 2500k... Last ShitterStone product I'll buy.

Thats what I'm running :/

Though mine has shown no signs of problems at all

What were you running your 7970s at? What was the draw at the wall? ~950w?
sr. member
Activity: 246
Merit: 250
Team Heritage Motorsports
Well, one thing I left out

The second PSU that I smoked- it blew a 20A breaker at a commercial building.(overnight)

I decided not to use one PSU anymore for that setup. I felt lucky the breaker blew

I sat and watched with the 3rd PSU- it would get pissed and shut itself off.

Doesn't everyone around here have a shitty PSU laying around?  It was really easy to jump- then wrap with electrical tape. Not white trash style or anything- do it classy.

I am using a $160 PSU with a left over free PSU. No problems
full member
Activity: 812
Merit: 108
I just smoked a silverstone strider 1500w running 4 7970's, not overvolted, with a 2500k... Last ShitterStone product I'll buy.
legendary
Activity: 1876
Merit: 1000
Well I of course believe you. I just had a lot of problems running all of that off one psu

I smoked 2 1250 w power supplies - and the 3rd keep shutting down so i separated the two and have had no real problems since.

Also 2.7 out of that machine.

It is all real nice and neat - just a cord coming out the back, a network cable out the back and the funny looking thing a power cable coming out the front- right under the hard drive.

Puts off a hell of amount of heat

I only buy SeaSonic psus now.......
legendary
Activity: 966
Merit: 1000
I have a rig running 3 5970s, 1 5850, and 1 5830 for 8 GPUs total.  It runs Ubuntu 10.04.

Power supply is an Antec TPQ-1200.  No problems there.

When fully clocked up it draws ~1330W from the wall, and crunches ~2.66GHps.

After a year of operation, it cooked the +12V pins on the motherboard ATX connector:
http://imgur.com/a/htewn

Now I'm using "molex mod" PCIe extender cables so that won't happen again.   See:
http://blog.zorinaq.com/?e=44
http://cablesaurus.com/index.php?route=product/product&product_id=28
sr. member
Activity: 246
Merit: 250
Team Heritage Motorsports
Well I of course believe you. I just had a lot of problems running all of that off one psu

I smoked 2 1250 w power supplies - and the 3rd keep shutting down so i separated the two and have had no real problems since.

Also 2.7 out of that machine.

It is all real nice and neat - just a cord coming out the back, a network cable out the back and the funny looking thing a power cable coming out the front- right under the hard drive.

Puts off a hell of amount of heat
-ck
legendary
Activity: 4088
Merit: 1631
Ruu \o/
I run 4x7970 overclocked at >2.7GH total on debian linux and everything else in the case with the one 1250W PSU and have done so for 6 months solid. Not all PSUs are created equal.
sr. member
Activity: 246
Merit: 250
Team Heritage Motorsports
Windows 7

12.8 - no SDK

4 7970's on 4 risers

1250 w PSU will work and crash after a couple hours-  4th card will run slow  < does not work- in fact will smoke the ps or thermal shutdown


1250 PSU running cards and processor-     and a crappy 400w psu running the board, fans, hard drive   
just jump the 1250 w power supply and leave it on - then boot the system 2nd

legendary
Activity: 1876
Merit: 1000
What build are you using with the 5 cards @100%?
- OS
- Driver version
- SDK
- CGMiner

I could only get them going at partial speed.

using the beta driver version that came out with the cards in Jan 2012.  so i think it is 11.7?
cgminer version 2.3.6
win7 64
ATI drivers are organized by (year).(month). If a driver came out in Jan of 2012, than it will be 12.1. 11.7 would be July of 2011. I think you mean the 12.1beta?

this is the name of the file for driver install:
amd_radeon_hd7900_win7_64.exe

it is based on the 2011 drivers i think, but not sure.
legendary
Activity: 952
Merit: 1000
What build are you using with the 5 cards @100%?
- OS
- Driver version
- SDK
- CGMiner

I could only get them going at partial speed.

using the beta driver version that came out with the cards in Jan 2012.  so i think it is 11.7?
cgminer version 2.3.6
win7 64
ATI drivers are organized by (year).(month). If a driver came out in Jan of 2012, than it will be 12.1. 11.7 would be July of 2011. I think you mean the 12.1beta?
legendary
Activity: 1876
Merit: 1000
What build are you using with the 5 cards @100%?
- OS
- Driver version
- SDK
- CGMiner

I could only get them going at partial speed.

using the beta driver version that came out with the cards in Jan 2012.  so i think it is 11.7?
cgminer version 2.3.6
win7 64


member
Activity: 65
Merit: 10
What build are you using with the 5 cards @100%?
- OS
- Driver version
- SDK
- CGMiner

I could only get them going at partial speed.
legendary
Activity: 1876
Merit: 1000
Thanks btcnut, this is what I was looking for. I have 3 7970's just cranking right now and stability is more important to me than purely maxing out the motherboard.

Sounds like 4 x 7970 might be the trick.

What power usage are you getting out of a 4x7970 set-up ?

I can get as low as 605w @ 925mhz if I downclock and undervolt

I run at about 650w with slight overclocking (while undervolting a little less) on the good cards to get about 580mhash/sec @ 162.5/w/card on average

I have 6 rigs with 5 cards each.  I run them at  930/680/0.937v  they pull about 850watts at the wall (~2750Mh)

before i started downvolting with msi afterburner during the winter. the same rig pull 1400watts at 3300Mh

I tried to get 6 to work.. I could NOT.  windows would load the device, but not the drivers. that being said, someone i know DID get 6 to load.

edit:  cgminer does not report the proper voltage.
Code:
cgminer version 2.3.6 - Started: [September 16, 2012, 5:13 pm]    Rig:miner17
miner17
(5s):2753.89  (avg): 2752.06 Mh/s  |    H: 114.4  Q:190937   A:291407   R:2095   HW:368   E:?%   U:34.57/m
TQ:?   ST:410   SS:?   DW:21871   NB:1886   LW:666670   GF:217   RF:1652
Connected to http://gpumax.com:8332 with LP as user ?
Value:
GPU 0: 74.0C 3254RPM 50% 124 | 550.6/550.5Mh/s | 97% | 930Mhz 800Mhz 1.17V A:58514 R:306 HW:0 U:6.94/m I: 9
GPU 1: 73.0C 2166RPM 36% 109 | 551.0/550.5Mh/s | 97% | 930Mhz 800Mhz 1.17V A:56124 R:927 HW:368 U:6.66/m I: 9
GPU 2: 73.0C 2388RPM 40% 113 | 550.9/550.5Mh/s | 97% | 930Mhz 800Mhz 1.17V A:58462 R:296 HW:0 U:6.94/m I: 9
GPU 3: 74.0C 2560RPM 41% 115 | 550.4/549.9Mh/s | 97% | 930Mhz 800Mhz 1.17V A:58980 R:291 HW:0 U:7.00/m I: 9
GPU 4: 73.0C 2113RPM 38% 111 | 551.1/550.5Mh/s | 97% | 930Mhz 800Mhz 1.17V A:59327 R:275 HW:0 U:7.04/m I: 9

edit2:
I run one of my rigs at 950, i dont know the exact watts
clock:  950/800/0.949v
Code:
cgminer version 2.3.6 - Started: [September 17, 2012, 9:05 pm]    Rig:minerwb
minerwb
(5s):2806.69  (avg): 2797.62 Mh/s  |    H: 126.4  Q:162541   A:235231   R:1222   HW:0   E:?%   U:34.6/m
TQ:?   ST:414   SS:?   DW:18328   NB:1502   LW:503642   GF:224   RF:1635
Connected to http://gpumax.com:8332 with LP as user ?
Value:
GPU 0: 73.0C 2389RPM 40% 113 | 561.1/559.5Mh/s | 99% | 950Mhz 800Mhz 1.17V A:46758 R:229 HW:0 U:6.88/m I: 9
GPU 1: 74.0C 2882RPM 50% 124 | 560.9/559.4Mh/s | 99% | 950Mhz 800Mhz 1.17V A:46820 R:266 HW:0 U:6.89/m I: 9
GPU 2: 73.0C 3573RPM 56% 129 | 561.4/559.6Mh/s | 99% | 950Mhz 800Mhz 1.17V A:47345 R:228 HW:0 U:6.96/m I: 9
GPU 3: 74.0C 2468RPM 44% 118 | 561.6/559.5Mh/s | 99% | 950Mhz 800Mhz 1.17V A:47274 R:269 HW:0 U:6.95/m I: 9
GPU 4: 73.0C 4631RPM 75% 148 | 561.6/559.6Mh/s | 99% | 950Mhz 800Mhz 1.17V A:47034 R:230 HW:0 U:6.92/m I: 9
member
Activity: 65
Merit: 10
Thanks btcnut, this is what I was looking for. I have 3 7970's just cranking right now and stability is more important to me than purely maxing out the motherboard.

Sounds like 4 x 7970 might be the trick.

What power usage are you getting out of a 4x7970 set-up ?

I can get as low as 605w @ 925mhz if I downclock and undervolt

I run at about 650w with slight overclocking (while undervolting a little less) on the good cards to get about 580mhash/sec @ 162.5/w/card on average
sr. member
Activity: 303
Merit: 250
What power usage are you getting out of a 4x7970 set-up ?

I'd expect a 850w should easily power all four.  Like Lethos mentioned, you'll run into a limit on how many available PCIe cables you can use from your PSU since most have up to six 6+2.  Currently, the Antec TPQ-1200 OC is the best valued PSU you can get right now.  It's on sale at NCIXUS for $120.
hero member
Activity: 535
Merit: 500
Well I already have over 15 GH in 5970's and 5870's so I am familiar with heat issues, pci slots, etc. I currently have a machine with 3 5870's and 2 5970's working fine using the set up I stated in the first post.

I had heard there were simply software limitations to going beyond 5 7970's regardless of pci slots, psu limitations, etc.

I can be happy with 4 considering they will eventually be used for scientific compute jobs, etc. and therefore crossfire capabilities are likely to prove useful.

Thanks again.
sr. member
Activity: 476
Merit: 250
Keep it Simple. Every Bit Matters.
Your limiting factor is usually the motherboard, since your will have to resort to risers on PCIe x1 slots, to make up for the lack of PCIe x16 slots.

Then comes the factor 7970 use 225-230w (6 + 8pin), so you quickly going to run out of cables and power even in the biggest of PSU's so needing two is not unusual for big rigs.

Different OS can give you problems, but as long as it's 64bit it should not be a limiting factor, if in doubt try linux.

The very nature of these boards also adds to alot of heat in a small space, so cooling this would be like having a 1-2k watt electric heater constantly on; I've had one of these in the past, they can heat up an entire apartment or small house by itself.

So most people should be able to do 4, but you could be able to go up to 8 if you go the extra mile. I can imagine trying to go beyond that is worth it with one rig. Split it apart and make another Rig. I don't know of many motherboards that even have than 8+ PCIe slots.
hero member
Activity: 535
Merit: 500
Thanks btcnut, this is what I was looking for. I have 3 7970's just cranking right now and stability is more important to me than purely maxing out the motherboard.

Sounds like 4 x 7970 might be the trick.

What power usage are you getting out of a 4x7970 set-up ?
member
Activity: 65
Merit: 10
Could not get 6x 7970s to work on Win 7 x64 on anything i tried
I got 5x 7970s on Win 7 x64 @ 80% clock on 11.12s. Cannot get 5 to work on anything else.
I got 4x 7970s on Win 7 x64 @ 100% clock on anything other than 11.12s

Havent tried winXP, there is some rumour that may work.
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