It looks like the 1600w psu has 2 12v rails.  I couldn't find anything about how the 2 rails are split among the connectors.

I also have 4x 1600w coolmax psus for sale.
This model: http://www.newegg.com/Product/Product.aspx?Item=9SIA24G2HZ2590&nm_mc=KNC-GoogleMKP-PC&cm_mmc=KNC-GoogleMKP-PC-_-pla-_-Power+Supplies-_-9SIA24G2HZ2590&gclid=COiArd-UncgCFQYKaQodjf0KxA&gclsrc=aw.ds
asking .80 BTC shipped(usa) OBO for each unit.

not everyone cares about power efficiency though. some of us here have access to low cost or zero cost power sources. 16 btc for a machine that barely mines 4 ltc a day? sure you can rent them out but yield is dropping in rental market due to shrinking scrypt coin market (monacoin switched to lyra recently)at most you can get 5 to 6 ltc over there.. anyone who will pay 1200 ltc for this miner will have to wait 250 days (most optimistical) on average just to break even..  
also difficulty is going to stay in 47xxx 50xxx range if not shoot upwards while ltc price is going to remain in shitters unless another ponzi pops up.
even 10btc for a price is hardly justifiable.. also just fyi official warranty period is over for these capricious miners so if they break you're on your own while Innosilicon and Alcheminer will still repair at cost..

I can confirm that 280x works on catalyst 14.12 when you copy both `amdocl.dll` and `msvcr110.dll` directly to miners folder.

Just used standard 280x settings with g2, w256 and I18 making 3,55Mhash/s
Didnt try to optimize yet.

Have two r290 i m in athens atm gonna send you details as soon ill be back propably thursday

buying siacoins - pm me with your price and amount you sell

speaking of hashrate:

Hash rate (last 1000 blocks)   88.784632GH/s
Hash rate (last 100 blocks)   196.982266GH/s
Hash rate (last 30 blocks)   341.852641GH/s
Hash rate (last 10 blocks)   1.865794TH/s

hash explodes - lets see what price does

to finally get some sell orders out, here is mine:

selling 2,500,000 sia for 1 btc

for those of you who tell me thats too expensive:

at the time of writing there are 766m coins supply
so 2,5m are 0,32 % of ALL coins at only 225$ (for that 1 btc)
that would mean a total cap of: 766 / 2,5 * 225 = 68,940$

if you check http://coinmarketcap.com/ and compare it to other coins that do NOT have a feature creating real value like sia
then you might see that my price is probably not expensive

good luck to buy cheaper than that