Memory bandwidth:
RX480: 256 GB/s
390X: 384 GB/s
ZEC uses a lot of memory operations. Do you still think that RX480 can work as fast as 390X?
my 390x claim to have a 512 gb bandwidth have i been lied to by the manufactures

Edit: i thoguth that the 7950"s have 384 gb bandwidth
You're thinking of memory bus, 512 bit.
here i thought memory bandwidth pertain to memory bus

It does
pertain to the bus, but is not equivalent to the bus. Bandwidth is the product of bus width
and memory clock speed.
512 bits / 8 = 64 Bytes
64 Bytes * (1500 MHz * 4) = 384GB/s
I'm running two reference 290's at 400h/s at 1030/1250 -100mv core -100mv aux 0 power level. Fans are now at 50-55% at 85C, this is inside of a Corsair 750D.
I need to put a kill-a-watt on it but it's made a significant difference on the temp with only a 20h/s loss. That's the highest core I can get to at the moment, stable.
Stock BIOS, should I load in the 390 STILT's bios?
One of TheStilt bios for the R9 290 should let you kick the temps down quite a bit while still bumping the clocks up some.
On ETH I'm routinely seeing 80C more or less at 1100/1250 under LINUX though I'm running the fans a bit higher than you are.
Thanks it means R9 290 and 390 have same speed with big price difference ?
390s can have a bit higher memory clock (and 8GB instead of the usual 4 on a 290) but are otherwise the same.
Today Claymore said
He likes 390-390X the most and he is going to reach 300H/s on stock clocks..
Hows this possible on stock clock on 390
Because they are already doing 230S/s+ and he is going to add more optimization.