if the s-3 can under clock / under volt like the s-1 it will be at .5-.6 watts .
say 400gh at 200-240 watt. it will be better then a sp30
Even at those numbers, they're close, but the sp30 still pulls ahead by a slight margin:
400 Gh/s / 240watt = .6 or 400 / 200 = .5
6 Th/s / 2400 watt = .4
Also price-wise very close (hardware purchase only):
11 x S3 = $5027.91 (at $630/1BTC today) / 5.357 Th/s (@stock 487 Gh/s, @550 if possible it evens it up)
$5,095 / 6 Th/s
Stock voltage:
11 x S3 = $5028 / 5.357 Ths / 4Kw
1 SP30 = $5095 / 6Ths / 2.4Kw
Undervolt assuming best case 400/200:
11 x S3 = $5028 / 4.4Ths / 2.2Kw
1 SP30 = $5095 / 6Ths / 2.4Kw
Now, the one thing that's going in the S3's favor is the form factor. The SP30 is harder for the home hasher to deploy since it's rackmount and it's going to be loud as all heck with all those fans. For us in a datacenter setting it makes more sense for the rackmount as our S1 deployment is nice but kludgey.
For today tho, it's still hard to beat used S1's if you have cheap power. Our average cost has been about $160 each, and they're very stable overclocked @205Ghs, so we have roughly 4.7Ths deployed for about $3700. Only after about 90 days it evens up and the S3's start to pull ahead counting power.