You indeed ARE a lucky person to have grabbed those 290X's for so cheap! Everyone
is in the mining craze (which is good/bad) and so many of the cards are hard to get,
well except for the 290X as the price is so high that profitability isn't there for the
performance.
First question is if you bought a reference cooler design or did you buy a GPU card
with an advanced cooler design, such as MSI Gamer card with twin fans and special
radiator? The reference design cooling system is awful and it will be very hard to
keep them cool while running high performance tweaks. Fortunately, NaN has very
optimized software that provides GREAT performance with much less power consumption
than cgminer (not a super fair comparison since one is MOMENTUM mining and the other
is SCRYPT mining). NaN keeps pushing the envelope though and each revision is faster
but does consume a little more power. Still WAY better than SCRYPT performance though.
The key to high performance is great power supplies (I use two Seasonic 860 Platinums)
using the proper PSU coupler (amazon for $29) and more importantly a good plan for
cooling. First step is to forget mining inside a case. Get yourself large plastic crates or a
wireframe rack. Next is to space out the GPUs properly! The farther apart they are, the
better. Actually the BEST thing you can do is make sure there is nothing in front of the
intake fans on the GPUs, that is the fans are pulling in fresh room air and NOT preheated
air from the GPU next to it. Having all the GPU's next to each other produces the cascading
heat effect where the GPU on the furthest right runs super cool as nothing is in front of it.
The next GPU gets pre-heated air from the GPU to the right of it, and so on and so on until
the furthest card on the left is running super hot. Same principal applies in cases but from
top to bottom.
Having said that, use some ingenuity to keep those GPU's cool! My goal is to keep them
under 80C while running full steam and better yet, keep them 70C or lower. It *CAN* be
done but requires some thinking *smile*. Keep the GPU fans running 85% or higher as
that is your first line of defense (closest to gpu/radiator) to keeping temps down. Sure it's
loud but you're mining.... PROTECT YOUR INVESTMENT.... second line of defense it to keep
cool air in front of the GPU fans.
Good luck!
Yea I got lucky and I managed to get these 4x R9 290X for $599 ea off Amazon.
Aside from my 4x R9 290X I have 3 GTX 780 which are pulling a measly 6500 cpm together....I bought those last year before I planned on mining. *shrug*
Now I'm just creeping around Amazon, Newegg, Tigerdirect, and Ebay until i find some rightly priced R9 290(x).
Edit: What temp are your cards running at? I just bought some 1x to 16x powered PCIE adapters and I think I'm going to pull out all but one of my GPU(s) from the case. The second card is making my top card run at 80C - 85C at all times with Fans @ 100%.....while second card stays at 60C-65C.
