Running seven 290x here. To make clocking them up easier in MSI AB (Because it's a pain adjusting seven different cards), I'm trying to find each cards best strap to allow me to clock all cards identically.
All the cards have been modified with 390x memory controller timings, clocked to 1000/1250 and DPM7 voltage reduced to 1150mv in BIOS. The strap I'm using I've copied to all higher straps so as to find the absolute best performance without timings changing with different straps.
For mining ZCash, it seems to favour core clock on RX cards, but on these 290x it loves fast RAM. My cards :-
Hynix CardsXFX Reference 4GB with Hynix AFR using Lard's 1000MHz strap. This one clocks well on RAM, with stock timings will do 1500MHz causing minimal memory errors in HWInfo.
MSI Gaming 4GB with Hynix AFR using Lard's 1125MHz strap. This one's a bit shit, causes total PC lockup with memory at 1450MHz with stock straps.
MSI Gaming 4GB with Hynix BFR using default 1125MHz strap. The best RAM overclocker with stock straps. Goes straight to 1500MHz, no errors.
Elpida CardsXFX DD 4GB with BBBG and using Stilt's 1250MHz strap.
2 x ASUS DirectCU II 4GB with BBBG and using Stilts 1250MHz strap.
Sapphire Strix 8GB with BABG and using default 1250MHz strap.
I don't know yet where these four Elpida cards will clock to with these straps..... Still testing.....
With old versions of Claymore, the Elpida cards, especially the Sapphire one, were the clear fastest. With V5 and 6 the tide has turned, the Hynix cards are ruling.
With all cards clocked at 1000/1350. Each of the Hynix AFR cards comfortably do over 170 sol/s, the BFR manages around 165~170 sol/s. Each of the three Elpida BBBG cards only do around 155~160 sol/s and the Sapphire card, which was the best card, is now the worst, it doesn't even make it over 150 sol/s.
I had drawn a conclusion that something "special" about the Hynix memory allowed them cards to be faster, something other than just memory timings, because all of the cards are running much tighter timings. The tighter timings have helped across the board, but still the Hynix cards are way out ahead.
However, another forum user here, Bardacuda (
http://www.overclock.net/t/1561372/hawaii-bios-editing-290-290x-295x2-390-390x/3300#post_25650552), has literally had the exact opposite happen to him. The Hynix cards started out as the fastest, and with tighter straps and new version of Claymore it's all flipped.
What conclusions can we draw from that other than, use tighter straps and higher RAM clocks to get best performance? But your Elpida/Hynix card and my Elpida/Hynix card may perform totally differently, even using the same straps and clocks.
Oh, and I'm fed up of editing BIOSes now.....