That's not what he was saying, though...

Using the typical 6-GPU setup, the motherboard ($80), CPU ($40), RAM ($30), OS drive ($20), and risers ($50) add up to $220 (may be more or less depending on sales and availability, but this is about as low as you're going to go most of the time while using a free OS).  Divide that by 6, and you have a per-GPU cost of $36.67.  I'm not considering power supplies, because you'll need almost the same amount of power for either of these options, though needing only one ATX connection would further reduce costs.  I'm also not considering the labor cost of setting up 3 systems with risers vs 1 system without risers.

For the 16-GPU board to be viable, the cost of the board, CPU, RAM, and OS drive combined must be less per GPU than $36.67.  That means about $586, minus CPU, RAM, and OS drive (let's say ~$90 for those items).  At around $500, this board would be comparable if you're using 3 consumer PSUs.  If you're using one of the 4K + PICO PSU configurations, the board is comparable at $550-$600.  If you are using a paid OS, you're saving 2x the cost of that, as well, so potentially $700-$800.  Personally, I think the time and troubleshooting savings of not dealing with risers, and their myriad potential points of failure, is probably worth another $200 itself for bigger farmers.

I would be shocked to see a custom 16-GPU solution like this at $500, but even double that would probably have a good market among folks like OP.

What location were you adding the offsets at? Because I don't think they can be added at A992 for cards that dont already have a programmed offset built in.
Maybe the learned folk on this thread could shed some light on how to go about adding an offset location to a bios that doesn't have one.

Kinda OT since this is a RAM Timings thread, but ill ask this anyways :

For Sapphire RX 470 4GB (Ref) cards GPU Core Volt offset is at A992 correct?
Now for the cards with Hynix memory, I find the default 04 which is 4 X 6.25 or +25mv, which seems legit.
But for the cards with Samsung memory, the value at A992 is FF which is -1 X 6.25 or -6.25mv, so something looks off.
Do different memory versions of the card have different default offset values? Or is the location different?

Any help/guidance would be appriciated.

shipping from?

WOW - thats a bold statement -- I would suggest doing a little more research before making wild statements like that, The Stilt is a well known and respected guy in the AMD world.  

In regards to the other comments, welcome to the club, several of us (myself, wolf0 etc) have put in countless hours

It seems that the real maximum size of GDS segments for RX 480 is 16KB.
It's a little disappointing, but still much better than 4KB without the kernel patch.
This number is also consistent with nertralph's report that Optiminer runs four CPU threads per GPU as GDS utilization can be maximized this way.
Now let me fix the kernel patch one more time...

Unstable?...12 GPUs at 82 hours +   (btw ignore the horrible eth hashrates...i just switched this rig over to eth and have been busy testing my prototype board so they still have ZEC bioses on them)

Yes there is no theoretical limit to what my solution will work with, should be fine with Nvidia cards as well. I am specifically testing with a mix of 470s/480s with 4/8GB

I'm curious if this custom solution will work with 8GB cards, or only with 4GB cards?

With any standard motherboard and some pcie multiplier you can do same thing !

With any standard motherboard and some pcie multiplier you can do same thing !