Bitcoin Forum

Do you think its possible 1 PSU can run 4-5 7970's in 1 system?

1500w+ for sure.

Yes. :P

what about 5 x 7970's with this: http://www.newegg.com/Product/Product.aspx?Item=N82E16817151109

This is what you need for 5. Average power consumption for 3 7970's is around 900w so 1500w for 5 including the mobo and cpu. That's if the power supply actually supplies a full 1500w.

Pssh, cmon. Undervolt that shit. You shouldnt need more than a 1KW PSU for 5 7970's, if that. My guess, properly undervolted/underclocked memory/max core @ 0.95v, it would only draw 750w at the wall.

I am running 5x 7970's using a single Sparkle Power 1200W 80+ (rated for 900W 12V @ 5 rails)

The total system power draw is 865W at the wall running the cards @ 950Mhz GPU / 900Mhz Mem @ 1.02V, 565MH/s per card.
The system consists of a 790FX-GD70, AthlonII X2 215, 4GB DDR3 and an SSD.

To get the most I could (power out of 15A home circuits that is...), I used two circuits (15A each) to split 3 rigs onto.....that looks like this:

(1 full machine & 'in-window' twin cooling fan per circuit, 3rd rig split over 2 circuits to keep from blowing breaker)
Circuit A also has a Dell 24port 10/100 switch (almost forgot about that...lol

All cards running @ 950Mhz GPU / 900Mhz Mem @ 1.02V, 565MH/s per card....(using CGMiner 2.4.1 defaults, Win7 x64)

http://members.shaw.ca/bitlane/powersetup.jpg


Both of the remaining 4-card rigs will also get their 5th 7970's installed as soon as the cards arrive.

Hope this helps some people, or gives a few ideas for those wondering....

For those wondering about specific setup...(not including the obvious single power supply 5-card/1200W PSU Rig)...

On the 2x PSU rigs, I use the 850's to power the Motherboard/CPU/HDD + 2 Video Card's External 8pin/6pin connectors (and of course all PCIe Slot Power by association).
The Secondary 650's get used for external Video Card power to the 6pin/8pin connectors to the 3rd, 4th and 5th cards (and perhaps additional cooling fans if required in the future).

That seems a bit high...

What is your MH/s per card ?...and are you overclocking/undervolting etc ?
Share some specs/settings if you don't mind.

@bitlane, choosing a x58 Mainboard may be not he best decision. It's Powerconsumption is way to high, CPU also.
But i see also you got a AMD Sys.

Couple of questions :

-does the underclock memory trick work with 7970s in Linux without needing BIOS flashing ?

-can 4*7970s at full overclock be used with a PSU of 1200W without power problems ( cards overclocked high ) ?

Thanks !

And ... where are my 7990s ??? Looks like AMD has given up :D

AMD licks balls with being limited to x16-x16 risers only in most x16 slots.

The X58 rigs allow me to run any width cable I want in any slot as long as it fits (obviously I can'y run an x16 cable in an x1 slot ;)  )

I just hate messing around with shorting pins etc. Also, my Xeons are 80W CPUs so it's not that bad.

In Windows:
Using CGMiner/ADL, memory spread is 150Mhz MAX.
Using 3rd party tools (AB, Trixx etc) can turn mem down lower.

In Linux:
No clue.

4x 7970 on 1200W, overclocked ?
Yes, I was running 1150mhz (650MH/s @ 1100Mhz...so higher obviously) on stock voltage (4 cards) and drawing 1000W at the wall
(using a Sparkle Power 1200W 80+ PSU rated for 900W max combined on 5x 12V rails).



June/July after some Equipment Show/Conference, also held back due to cooling problems and Nvidia Dual-GPU release.

Have you found some to be a bit flaky with mem under 850Mhz ?

I am running my mem @ 900Mhz because I was crashing CGMiner at times (regardless of voltage increases). I've now been stable for nearly 48hrs with mem @ 900.
(950Mhz GPU, 900Mhz Mem, V-1.02, 565 MH/s each)

I have 5 on enermax platimax 1500W, running them at 1100MHz@1100mV, didnt measure the draw with that configuration and settings but i assume its about 1300-1400W or so (free power so fuck it :))

OP Please keep in mind that power draw at the wall is not the power the PSU is giving to the cards. For example if I were to ask my PSU for 1000W and it is 87% efficient (80 PLUS Gold 100% efficiency), then the actual draw from the wall would be 1000/0..87 = ~1150W.

That being said, you might also might want to think about how you're powering all this equipment. Most house circuits in the US are 15A circuits which means you have a really good chance to trip your breaker if you power anything else on that circuit.

June 6th, Computex 2012.

What about running 4*7970s on 1250 MHz and lowest memory BIOS flashed ??? On AX1200 or SS 1250W models ?

At those speeds, I wouldn't want to deal with the heat and unnecessary power requirements to reach 1250Mhz.

As I said (and can be seen on the BTC Wiki under Hardware Comparison) 1100Mhz gets you 650 MH/s per card. If I recall, 1150 got me roughly 675-680 MH/s.
Unfortunately at that point, heat started to become a concern for me, as I like to run my cards cool and use a 69c target temp and make sure my fans run under 50% 24/7 to achieve it.

Here is a screenshot of my 3x 7970 rigs. As you can see, I am loosing performance but notice my temps (it's also warm today) and I explained my power draw earlier in the thread....this setup runs very efficiently for what it is. (voltage doesn't report correctly through CGMiner API, all voltages should read 1.02V).
With more power available to me, I could easily clock these 3 rigs up and add 100+ MH/s to each card (so, 1.4GH/s total)....but again, at the price of power that I don't have....and heat that I don't want to deal with.

This is a custom web monitor using the CGMiner API.

http://members.shaw.ca/bitlane/7970rigs.jpg

I am currently running 14 (soon to be 15, last card should be here in a day or so, was on backorder) of these:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814125408
Gigabyte 7970 Reference Models.

Can you link to the model cards you are using?

I have been using XFX Blacks and bought several of the HIS when they were on sale on Newegg Business. I have not been able to get them stable at the voltages you are setting with yours. Another poster was able to run his Gigabyte cards with the triple fan setup at .88V. So before I order more cards I like to see the other options.

I put a link to the cards I am using at the bottom of my post above.

Thanks for that. It seems like the Gigabyte cards are the ones that can get lowered in voltage the most. My HIS cards take a total shit with anything less than 1.1. You cards and another posters are both getting great voltage numbers and both are running GB cards. I have 36 7970s now and none of them are Gigabyte.

I have 24 XFX Black Editions and 12 HIS. I am not super happy with either's performance.

Edit: Any plans to release your custom monitor code?

I decided to try and up the overclock a bit more (+10Mhz), from 950 to 960Mhz on each GPU to see what would happen.
It had no effect on the power readings on the UPS's (which probably means I could undervolt a bit more if I wanted to) and the cards are now running at approx 573 MH/s each. I will run like this for a day or so and try more after I confirm this is stable.

I actually didn't write it.
You can find it in the Mining Software Section. It was written by jjiimm_64. I changed it a bit, but it's his project....and available for free.
"CGMiner Web Monitor"

<EDIT>
Here you go.....
https://bitcointalk.org/index.php?topic=58834.0

So I did some basic math at 11 cents per KW. With all the component costs static and the only difference being your 5 cards versus 4 cards at different clocks.

I have 1150w producing 2600 hash to your 865 watts and 2825 hash. That is with 4 and 5 cards respectively.

When you add in the extra cost of the 5th card you will generate 2% more money in the same 8 month period of time if you sell your cards for the same per card amount as the 4 card user.

That is based on someone buying 7970s about a month or so ago and mining until the reward halfs.

That is if I did my math correct.

If the difficulty stays the same and the price stays the same after the reward halfs you would be making about $1.10 more per day per rig than the person with the stock voltage 1100mhz miner.

I'm seeing a lot of bad advice on here. A lot of miners think its best to fit whatever they can on a power supply. They justify this buy claiming a good brand name can handle it. It's easy to burn up a power supply mining. The extra heat reduces the life of the power supply and lowers the efficiency. The closer you get to max load also effects it. Anything over 80% load is asking for trouble.

http://www.silverstonetek.com/images/tech/WB10-005/10005-1.jpg

I just updated with the latest version.

bitlane:  you should update yours..  you would like the heatindex.

bitlane, I was asking if it could be done.

Leave the power and heat requirements to me.

Anybody know what memory speeds to flash for 7970s ?