Quote from: Trillium on February 25, 2014, 11:57:02 PM

Quote from: klondike_bar on February 25, 2014, 10:43:49 PM

looking for a bit of a confirmation on a build before I go out and throw down $2000+ on it:

MSI Z87-G45 GAMING ($160)
2*600W power supplies (full 600w on 12V) ($40 each BEFORE a $15 MIR)
cheap celeron processor (about $50-70)
2x2gb ram ($40)
6x Sapphire R9 270X dual-x ($240 each)
6x usb risers ($25 each)

USB w/ BAMT
keyboard
mouse
monitor

Does this look like a good build? Ive read the sapphire cards can be pushed into the 450-480 khash range, so 2.7Mhash/s for about $2250. ($0.80/khash) I plan to use either a milkcrate or a shoerack and a few zipties to hold everything in place.

My biggest concern is of being late to the game. scrypt ASICs are close, and will offer about 1/10th the power draw. I expect these to roll-out on a large scale in the next 2-3 months. The GPU rig would require about 6-9 months to break even - maybe 3-4 months if mining doge, having BTC value rebound, and considering a 50% resale value on the components to gamers.

Buy quality PSU from companies like corsair/seasonic/OCZ. $40/ea implies generic worthless junk. Probably nil stability on 12v lines or will fail quickly.

For the upper CPU price you list, you could almost get the better http://ark.intel.com/products/77775/

Depending on retail prices, might be cheaper to get non-X card variety, which can be bios modded to run at ~1100 mV to give 430-460 kh/s @ as low as 130 watts per card. Although mods like this could probably also be applied to X cards.

Refer my PM for cheaper risers.

Scrypt ASICs will be inherently limited by RAM - which was the original reason why scrypt was chosen? - which translates to very high purchasing prices for customers. I would say that we're going to see similar final ROI times between GPU and Scrypt ASIC. One is cheap but burns a lot of power, one uses nil power but capital is very high. Also in regards to your estimates, keep in mind that only a month or two ago ROI time for a rig like this would be 40-60 days. If markets rebound quickly and you are willing to wait without cashing out... Cheesy

saw your PM - i actually ordered some ebay risers last week but at this point might still buy locally for $10 more just to get things going sooner than later.
on review of some other builds - it looks like going with a 4-slot mobo would be almost $100 less than a 6-slot variant, and that BAMT can run on only 1-2gb of ram (another $20 saved)

after some price checks, it looks like the local Tigerdirect actually has very good deals and is competitively priced against NCIX.ca and newegg.ca - They had about 12 of the Sapphire r9 270x in stock today (only 2-3 of the MSI 280x) at a recent price drop from 270->240. a few different guys in the store knew i was looking for mining gear before i even told them, and pointed out a few good mobo brands (in 6-slot flavors).

RONA has some amazing storage crates that are about 20% bigger than milk crates and I currently use some for holding 2 antminers + psu each. using one for a GPU rig would likely be pretty simple and extremely easy to stack.

few remaining questions:

1) AM3 vs 1150 vs 1155? It looks like these all offer similar benefits, but AM3 seems to be about 10-20% cheaper for both the mobo and the CPUs
2) any issues i might run into using zipties to support the cards and mobo? obviously i dont plan to let them be loose and swinging around, but without a GPU in fornt of me its difficult to visualize the tie-points i could/would use.
3) if using USB risers, should the mobo be vertical? most builds have the mobo flat but this seems like an invitation for dust buildup or for foreign object to land on the board and short something. with a crate, vertical orientation seems simple and better
4) anything else i should consider? Is it as simple as assembling the rig then booting it with a BAMT-loaded usb drive and then tweaking settings from there? do i need to run a monitor from the mobo or one of the GPUs and do i need dummy plugs?