Tell me where I can get an 800 KH/s rig for $400 ($.5 per KH/s) and I will delete this post.
You don't build 800 KH/s GPU rigs, a typical rig of the past couple of months would be 6x R9 270, and it can do ~2.8 MH/s. Cost ~$1100 for GPUs plus "infrastructure".
Before R9 280X prices went crazy you could build a very nice 6 GPU 4.5 MH/s rig for $1800 + "infrastructure". Now prices seem to be coming back to normal, so that could be possible again.
There is also the GTX 750 Ti, not as cheap in $ per KH/s, but much more power efficient, somewhere in the middle between Gridseed and AMD GPU.
There is no need for a massive expensive PSU, two mid-range 600-850W PSUs will do nicely and will be cheaper. There is the ASRock BTC motherboard available for ~$70 (6 powered PCI-Express slots). Cheapest CPU and RAM will do just fine. HDD is not necessary, a $10 flash drive runs BAMT.
The point is, you can overengineer and overspend on any solution, but a well though out GPU rig does not come even close to $1 per KH/s AND is a lot more versatile than Gridseeds (think Vertcoin or Heavycoin). On the other hand, you can put a handful of Gridseeds on your desk and have 1.5 MH/s literally in minutes. Each has its benefits if you know what you're doing.
Just a few months ago, when, after looking over ALL the options, GPU's were overall much more expensive than GridSeeds, and on average still are. Especially where power consumption and maintenance go. They are also noisy, cumbersome space heaters!
At that time, $1 per Kilo hash for a top of the line GPU was conservative!
No matter how cheap 500KH/s etc. GPU's can be had, they will always be grossly power hungry by comparison! This is a MAJOR factor in itself! The more one spends on Kilo Watts, the less money one puts in their pocket! Period!
No matter what anyone says, no matter the calculations and rationalizations, GPU's are still and always will be more expensive to own and operate than ASIC's. Namely, GS5's - Period, end of story....
To be fair, the only 'obvious' advantage a GPU has over ASIC's is Algorythmic versatility!
Then again, FPGA's are Algorithmically versatile as well and just as efficient as ASIC's. Just not as commonly available as GPU's, unfortunately. But that is changing in due course!
GPU is a fancy video card that has it's primary and original purpose completely circumvented by use as a miner. That use goes completely to waste! POOF!
No such off purpose waste with ASIC's or FPGA's. NONE!
Overall, I just can't justify using a GPU over GridSeeds. What ever processing speed GPU's have over GridSeeds 1 for 1, is completely negated by the overall efficiency thereof!
GPU's are a dying technique headed for the status of relic where mining is concerned.
They are headed back to doing only one thing. Driving LCD's!
That is who GPU owners will be selling their used video cards to in the future. GAMERS!
Wolfey2014
