So what is the consensus on how many 7970's can run on one rig ?

[jjshabadoo]

I thought I saw that 5 was the limit in windows 7 64bit.

Anyone get 6 to run yet with newer drivers or a specific driver ?

I have msi gd70 motherboards so I'm all set with pci slots, etc.

Also, do these run OK with x1 risers?

Thanks in advance.

[segabtc]

I was under the impression that the limit was 8 GPU per AMD, windoze is 8 if you have the correct version, but most is 4 or 6 gpu. Hope you have a Large or multiple power supply for a rig like this.

[crazyates]

The ATI drivers limit limit to 8. 32 bit Windows limits to 4. Most motherboards have their own limit tho, 3, 4, 5, etc.

[jjshabadoo]

I understand the 8 card(gpu) limit but if I remember correctly, people just couldn't get more than 5 7970's working no matter what they did.

I have 8 GPU's going on one rig now, but all 5970 and 5870's. Most of mine have 6 gpu's minimum.

So I was wondering if those who have 7970 rigs could chime in. I remember jimm_64 saying he couldn't get more than 5 running in windows and he has many 8 gpu rigs (4x5970's)

I have the MSI GD70's and all the good mining parts, seasonic 1250 watt gold psu's ,etc.

Just don't want to buy a 7970 and be stuck with one extra as I have a rig with 3x7970 flying away right now, but I would like to max it out for efficiency.

Thanks.

[btcnut]

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.

[jjshabadoo]

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 ?

[Lethos]

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.

[jjshabadoo]

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.

[scifimike12]

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.

[btcnut]

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

[jjiimm_64]

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

[btcnut]

What build are you using with the 5 cards @100%?
- OS
- Driver version
- SDK
- CGMiner

I could only get them going at partial speed.

[jjiimm_64]

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

[crazyates]

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?

[jjiimm_64]

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.

[jborkl]

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   <that works fine

just jump the 1250 w power supply and leave it on - then boot the system 2nd

[-ck]

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.

[jborkl]

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

[Bogart]

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

[jjiimm_64]

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.......