2 rigs  12 rx 470 4gb sapphire oc eddition
both 863 h/s constant

I have no rejects on the EU server

Your 290x's should be getting minimum 175 Sol/s.

personally i choose XFX RX 470 Black 4gb .. can undervolt a lot and overclock core and memory a lot,along with timings,great card for price.

I have some of these , they are voltage locked man you cant undervolt them outside of bios mod or wattman

I would say rx 480 4gb.. much more cheaper than the 8gb version (even cheaper than the 470 8gb, at least in my country).. almost similar performance in term mining zcash... in my case rx 480 consume less power than the 470..

here's the hashrate of my sapphire nitro rx 470 8gb & rx 480 4gb:

the gpu 0 = rx 470, gpu 1 = rx 480

-------------------------------

ZEC: Share accepted (329 ms)!
ZEC: 11/16/16-02:14:11 - SHARE FOUND - (GPU 1)
ZEC: Share accepted (312 ms)!
ZEC: 11/16/16-02:14:20 - New job from equihash.usa.nicehash.com:3357
ZEC - Total Speed: 307.922 H/s, Total Shares: 1435, Rejected: 3, Time: 01:04
ZEC: GPU0 152.638 H/s, GPU1 155.285 H/s

ZEC: 11/16/16-02:14:27 - New job from equihash.usa.nicehash.com:3357
ZEC - Total Speed: 307.292 H/s, Total Shares: 1435, Rejected: 3, Time: 01:04
ZEC: GPU0 152.107 H/s, GPU1 155.185 H/s

ZEC: 11/16/16-02:15:24 - New job from equihash.usa.nicehash.com:3357
ZEC - Total Speed: 306.654 H/s, Total Shares: 1442, Rejected: 3, Time: 01:05
ZEC: GPU0 151.656 H/s, GPU1 154.998 H/s

ZEC: 11/16/16-02:15:50 - New job from equihash.usa.nicehash.com:3357
ZEC - Total Speed: 308.496 H/s, Total Shares: 1449, Rejected: 3, Time: 01:05
ZEC: GPU0 152.233 H/s, GPU1 156.263 H/s
ZEC: 11/16/16-02:15:55 - SHARE FOUND - (GPU 0)

ZEC: 11/16/16-02:16:23 - New job from equihash.usa.nicehash.com:3357
ZEC - Total Speed: 310.850 H/s, Total Shares: 1459, Rejected: 3, Time: 01:06
ZEC: GPU0 153.520 H/s, GPU1 157.330 H/s

ZEC: 11/16/16-02:16:45 - New job from equihash.usa.nicehash.com:3357
ZEC - Total Speed: 312.392 H/s, Total Shares: 1461, Rejected: 3, Time: 01:06
ZEC: GPU0 154.383 H/s, GPU1 158.009 H/s

ZEC: 11/16/16-02:17:27 - New job from equihash.usa.nicehash.com:3357
ZEC - Total Speed: 312.066 H/s, Total Shares: 1466, Rejected: 3, Time: 01:07
ZEC: GPU0 154.624 H/s, GPU1 157.409 H/s

ZEC: 11/16/16-02:17:44 - SHARE FOUND - (GPU 0)
ZEC: Share accepted (328 ms)!
ZEC: 11/16/16-02:17:52 - SHARE FOUND - (GPU 1)
ZEC: Share accepted (329 ms)!

ZEC: 11/16/16-02:18:15 - New job from equihash.usa.nicehash.com:3357
ZEC - Total Speed: 310.241 H/s, Total Shares: 1477, Rejected: 3, Time: 01:08
ZEC: GPU0 154.255 H/s, GPU1 155.986 H/s

ZEC: 11/16/16-02:19:42 - New job from equihash.usa.nicehash.com:3357
ZEC - Total Speed: 306.195 H/s, Total Shares: 1488, Rejected: 3, Time: 01:09
ZEC: GPU0 151.096 H/s, GPU1 155.099 H/s


GPU #0: Ellesmere, 8192 MB available, 32 compute units
GPU #1: Ellesmere, 4096 MB available, 36 compute units
ZEC - Total Speed: 306.965 H/s, Total Shares: 1497, Rejected: 3, Time: 01:10
ZEC: GPU0 151.138 H/s, GPU1 155.827 H/s
Pool switches: ZEC - 0
Current ZEC pool share target: 0x001e1e1e (diff: 2176H)


ZEC: 11/16/16-02:21:05 - New job from equihash.usa.nicehash.com:3357
ZEC - Total Speed: 308.673 H/s, Total Shares: 1501, Rejected: 3, Time: 01:11
ZEC: GPU0 151.308 H/s, GPU1 157.366 H/s


ZEC: 11/16/16-02:23:05 - New job from equihash.usa.nicehash.com:3357
ZEC - Total Speed: 308.596 H/s, Total Shares: 1525, Rejected: 3, Time: 01:13
ZEC: GPU0 152.859 H/s, GPU1 155.737 H/s
------------------------------------------

(I erased the "SHARE FOUND" list to make my post shorter)

with the same core and clocks a 480 will consume 10% more than a 470  no way it cosumes less

let me revise that to say each card is in a 6 card rig not standalone.

also what are you doing to get the higher 15 h/s? i haven't touched any of the stock settings.

thanks!

************EDIT***********

I was looking at the wrong gpu's.... in that 5 card rig there are 5x r9 290x each doing between 144 - 151

thanks!

using -i 4, GPU clock 1100 & mem clock 1500 my r9 280 non x is getting about 125h/s

v4.  556 watts 130 sol stock 2x380 strix + 7950 vaporx

 v5.  500 watts 178 sol stock 2x380 strix + 7950 vaporx

v6.   500 watts 270 sol stock 2x380 strix (82 sol each) + 7950 vaporx (105 sol)