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Just wanted to share my latest rig that turned out pretty well after some tweaks.

• 6 x Asus R9 270 DC2 @ 1135/1500
  Gigabyte 990FX AM3
  2GB DDR3
  Sempron 145
  Corsair CX750 750W
  Fractal R2 750W
  Add2PSU
  6x x1->x16 powerd risers
  USB-stick with BAMT 1.4.1 "honeybee"

2940Kh/s @ 975W (Whole system)= 0,33W / Khs

Compare to my other rig with 3x280x
2160Kh/s @ 910W (Whole system) = 0,42 / Khs


I belive the 270's "non-x" are great value right now, u can squeeze almost 500kh/s (475-490) from them for ½ price (210$ in Sweden with BF4) of the 280x (385$).
My kill a watt-adapter measure's values from 940-980W @ wall on 100% load. I downclocked the CPU and no connected fans.

Settings? I can only get 423khash stable with my 2x 270x's  :'(

],
"api-listen" : true,
"scrypt" : true,
"auto-fan" : true,
"expiry" : "120",
"failover-only" : true,
"gpu-dyninterval" : "7",
"gpu-threads" : "1",
"gpu-engine" : "1135",
"gpu-memclock" : "1500",
"gpu-powertune" : "0",
"intensity" : "19",
"log" : "5",
"lookup-gap" : "2",
"per-device-stats" : true,
"queue" : "0",
"thread-concurrency" : "15508",
"temp-cutoff" : "90",
"temp-hysteresis" : "2",
"temp-overheat" : "80",
"temp-target" : "72",
"vectors" : "1",
"worksize" : "512",
"verbose" : true,
"kernel-path" : "/usr/local/bin"
}

280X still better price/performance

How is that? the 280x isn't twice as fast yet it costs twice as much.

280x MSRP is around 320 - 350.  So not 2x as much as 270.  Also KH/Watt is better on the 280x than the 270.

Not in the US. Cheapest 280x available at newegg is $499. There are some of the lower clocked 280x's at amazon for $469... vs. 270's @ $200-229

Last week you could've had most 280x's for $400 easily.  This week the lowest I'm seeing is $449 from reputable vendors.  Prices do fluctuate.  But the KH/Watt is still much better for the 280x than the 270.

http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=8573335&CatId=7387

Stop talking nonsense. This card costs way too much and doesn't offer a performance increase by the same factor. In addition to the 270(and x version) being more energy efficient (plus only 1 cable).

I've lurking around for making my mining rig. Especially R9 270's have my interest.
Your topic + pics of the rig got me intriged.

I guess you undervolted the 270's. What made you do this since i saw this voids the warranty? Or can you just put the original bios back up there and they can't see it.? What where your steps here (vbe7 and cryptobadgers guide)? What voltage seems to be completely stable?

I was thinking of using 1 platinum 1200W psu on bamt, no hd, cheapest intel sempron cpu. Think this would pull it off ok?

on my 270 from powercolor on windows i can take 475 max with same settings, except clocks 1150/1500 and th - 24000

MSRP is one thing, current retail prices are another.

280xs are going for 400+ easily, closer to 500.. at least over here in the USA.

Even the 270s are 220-240.

280x costs 2 times (or more) than the 270 non x. Look up the prices, just about anywhere.

OP, it's just one. For many, the higher density of 280x is convenient, so is the high shader count for non-scrypt coins. Furthermore, the R9-280 and R7-265 (rebranded 7950 and 7850) are going to be introduced.

Then, with 270's, why did you go dual-PSU? Couldn't you get a EVGA 1300W?

Either way, I don't want to distract. Great rig, congrats  :)

Which means that your initial sunk cost is higher with a 280x rig. However, with an equivalent number of cards, the 280x rig would hash at 1.5x the rate of the equivalent 270 rig. The difference in power cost is fairly negligible at current likely profit rates, so the amount of profit realized through time with the 280x rig is much higher.

Does a (non x, non gigabyte) r9 270 use more than 150W under full load? They only have 1 6pin connection...
Was thinking... 6 of those 270's = 900W max + some new cpu, ram, ... = 100W -> 1000W total usage. Does this seem correct and would a 1200W gold/platinum pull this off?

Like everyone has said 280x go for 4-500. Thats extortion as I got mine for $300. However, I just picked up two 270s for $199 on amazon.

sry for delayed answer, to much work... :/
My wholse system with 6 x 270 "non-x" consumes about 975W, say 125W for the mobo + other stuff = 850 / 6 cards = 140+ W /each, and the 6pin can only pull 75W, so the rest 67W/card need to be fed from the pci-e, and therefore is very important to have powered-risers. A 1200W gold/platinum would do the job no problem, just make sure it has 1 12V rail with 70amps+.

cheers!

The Mobo only has 2 x1 x16 PCI-e slots and 4 x16 x16. Are you using x1 x16 powered risers in the x16 slots?

Hey mate, no prob at all, i'm glad i got a response since im on the edge of my seat wanting to order everything...

To reach that '975W', did you undervolt any cards or is this just not worth it with r9 270's? Reason i ask is because:
1) We void the warranty flashing r9 270's bios since they dont have dual bios switch like the 270x.
2) It might not be worth the hassle.

You undervolted the cpu, was that worth it? i believe newer cpu's only use like +-50W.

I would use those USB pcie risers on my ASRock H81 Pro BTC, which come with molex to be powered. Would you make them powered all 6?

I got my eyes on this psu: http://www.super-flower.com.tw/products_detail.php?class=2&sn=16&ID=94&lang= (http://www.super-flower.com.tw/products_detail.php?class=2&sn=16&ID=94&lang=).
Output +3.3V@20A ; +5V@20.0A ; +12V@99.9A ; -12V@0.5A ; +5Vsb@2.5A
12v rail seems sweet right?

thanks for sharing..

Then go buy a hundred 290x, they will hash more.

Congratulations for your new rig. Wow, 6 GPUs.


There is no "gpu-vddc" mentioned. How did you undervolt then?
If you haven't undervolted yet, that is a major source of massive energy savings.

While I discovered how to do it, I documented it all in this thread; may it help you, too:
https://bitcointalk.org/index.php?topic=395004

 ;)

Hi!

1) I did not undervolt any cards, all stock volts, if you intend to overclock, undervolting might be a hassle anyway.
2) i dont think you need to flash the bios at all to get nice results.
3) The undervolt/underclock of the cpu was probably not nessesary at all, i was just having some initial problems with the power consumption so i tried to minimize the consuption form every device connected to the mobo, but later i found out that it was due to no 5V load on the 2nd PSU, and after i solved that issue i just didnt change the cpu back.
4) Yes i would try to power all the risers, since most 270 cards only have 1 6pin (75W) they will draw the rest (75W) from motherboard (risers).
5) that psu looks really sweet on the specs, never seen the brad do.

cheers

i did not undervolt since i intended from the begining to overclock.

You are going to destroy those cards in no time.

Why? My 7950's has been runing oc'd since April -13 no problems :D

Why would that be? As long we keep an eye on the temperature, it should be ok...
Extra fans blowing on the 6 gpu's would be advisable i guess...

Ok, fine, that's just for precaution. Of course yours could be fine, however someone that reads this, ends up with the impression that theirs (other mfg, other coolers, other components, different ambient temperature, less care, low fan speed, etc...) will too.

If you want to debate the point, before, just read other threads and other forums with people toasting their cards...

Yes ofc im aware that you will shorten the expected life of the cards. I belive this should be common knowledge around here. Im happy if they last a year or so. Good point made do

Of course, you don't have to, but you will have to live with higher temperature, louder fans, more electricity consumption, higher bills, more greenhouse effect - and perhaps even earlier death of the cards.

Even with overclocking, I would give it a shot how far you can undervolt.

And considering the maxing out, running at highest possible khash/s regardless of anything else - read my opinion here if you want to:
http://ecoiner.org/mining-hardware/save-electricity-save-money-undervolting-7970-xfx-self-vbe7-bios-1017/

:-)