280x (x3) cgminer troubles. Low hashrate. 2,000 Doge.

[cherominerito]

I need your help.

I have got 3 Sapphire 280x and I get 1.6 MH/s (550 KH/s each). 2 days ago I got 700 each and I don´t know why. I reinstalled W7 64 bits and lastest drivers but nothing changed.

I offer 2,000 Doges to someone who solve my problem.

Thanks.

Edit:

setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
C:\cgminer\cgminer --scrypt -o XXX -u XXX  -p XXX --lookup-gap 2 --thread-concurrency 8192 -I 13 -w 256 --auto-fan --temp-target 72 --gpu-memclock 1500 --gpu-engine 1020 --gpu-powertune -20 --expiry 1 --scan-time 1 --queue 0 --no-submit-stale

If I use -g 2 hashrate come down to 400 each.

[rwessels]

Clock them between 1025 and 1080 - move up in 5 mhz until you get the optimal rate.  Make sure you have power limit set to 20.  Make sure the cards are running less than 80 degrees.  Anything more and I notice mine start slowing way down due. 
Set gpu threads to 2 and intensity to 13.

[duniek]

did you solve a problem?

once i installed 4x 280x on 790fx-gd70 they are hashing 720 all night(avg was 2850), suddenly hashrates drops to 2100 (530 per card)

I switch mobo/ram even format hdd and put clean OS on it and now i get 530avg per card
WTF

[Wipeout2097]

You shouldn't install the "latest" drivers. Go back to 13.12

[PhattyBanks]

yeah go back to 13. drivers if you are on 14. drivers

this is my config for 755k on 280x vapor x

setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
C:\cgminer-3.7.2-windows\cgminer.exe --scrypt -o stratum+tcp://poolcoins:3349 -u user.1 -p x  --thread-concurrency 11200 --lookup-gap 2 --gpu-engine 1080 --gpu-memclock 1500 --gpu-powertune 0 -w 256 -I 13 -g 2

[duniek]

I am using 13.12 drivers from the beginning

I have R9 270 (hashing 480 easy) and r9 290 (hashing 840 easy stock settings, 890 with OC), now i bought 280x and get problems

I realized I have gpu threads "1"  instead "2" - after i change it on "2"  - magically i get 720 on card (I tested it on one card)
after when i plug two more cards, - the same script - i got 550 AGAIN ***************

I write in cmd this sync objects 1 and alloc percent 100 - got 630 per card

I dont know how to make it for 700+ khash



/////edit

reboot
delete cgminer folder, unpack again put script on it

1050core/1500mem
I got 720/720/660

finally!!!!!!!!!