Running @ difficulty 2048 - discoverd that vardif pool ports are bad for my units - if for some reason they drop under 300 -- they will not recover - stop hashing... Happened all the time on the BE Controller; & initially when I went to the Minera RPi image -- haven't switch back to a vardif port since -- pool I mine doesn't have ability to set difficulty.

I down clocked to 230 - earlier today (about 5 hrs ago) - and added a fan (at 4:05pm on the graph below) blowing on the side of the 2 prismas - wide variance in poolside hashrate - seems better the last hour with fan and clock 230 - Minera Error/Reject Rate @ 3.84

http://i.imgur.com/w729eeT.png

From what I can find it in Minera forum posts appears that is the "load" on the RPi resources. 
I currently have 2 Prisma on my RPi using wired connection and my RPi shows Green

http://i.imgur.com/OG3oJIw.png

Try pointing them at a pool port set for difficulty 2048 (S4).
I seen issues when when it comes to pool port set to vardif - units would hash for 1-1.25 hours then stop hashing - when this happen the difficulty would drop below 500 then bottom out and stop hashing till BE Controller was rebooted; had a similar experience on the RPi except it managed to hash for about 2.5hrs before dropping out.  Since I changed to pool port set to 2048 it has been going non-stop for over 21.5 hrs.

I currently have 2 prisma using CG Minera Rpi image - with AM CGminer fork - running great.  When I used the BE Controller the I could only have 7 of the 8 hashboards going - if I tried all 8 - one of the boards didn't work 85% of the time and had chips on 1 board go into PwrDn state (around 13 on both physical & logical blade).

Screenshots below are pool report hashrate, minera, & CGMiner output.  The drop in hash around 5pm seems to be pool or internet related as my 10 S3s also experienced a drop at the same time.

http://i.imgur.com/yxqjoou.png

http://i.imgur.com/HZNK8CT.png

http://i.imgur.com/9tBewQm.png

[We did not participate in group buys, this is our own experience]

Hi, so, this has been a total nightmare.  But, I found this information posted by CrazyGuy to be reliable https://bitcointalk.org/index.php?topic=795477.0 and he points out flaws with the dip switches and notes on the "virtual boards".

Also, 3/16 of the prismas I've received had caps rattling around the boxes.  I have 5 of our own I've yet to open, 4 from a customer I've yet to inspect.  These all came straight from AM.  Also the Tube we received, I'm guessing as compensation, had components that had fallen off in the shipment.  This has been a total disaster. 


[/quote]

Question as to the packaging - are your units packed with the 4 blue tubes keeping the prisma in place or did they have 4 white squares shaped pieces of foam to keep the prismas from shifting?

I have 2 working units from CG GB on hand my batch1 unit had 4 white square pieces of foam & the prisma had shifted in shipment. the 2nd unit I got AM had changed to using blue foam tubes (a bit bigger) and the unit had not shifted during shipment.

Got another unit on the way from Canary's GB.

Luckily both of my units so far are working great since I have moved from the BE Controller to the Minera RPi image that CG created. When on the BE Controller it couldn't handle 8 hashboards - 1 board would cause the unit to stopping hashing after 1hr - 1.25 hrs.
Even on the RPi the unit seems to have issues if I use a pool port that is set for vardif - using a port set to difficulty 2048 works great though.

http://i.imgur.com/0RRLSU0.png

Restarting CGMiner or switching to the CGMiner 4.x (Official) then back wouldn't clear it for me.

From Settings change from CGminer (ASICMiner Fork) to CGminer (RockMiner Fork) - SAVE & RESTART then change back to CGMiner (ASICMiner Fork) - SAVE & RESTART.

Not sure who mentioned this solution previously but it has been working for me.

My 2 Prisma are still hashing great off RPi after almost 17hrs. 
Have a 3rd unit that is on it's way; will report in once I get it added to the chain.

http://i.imgur.com/7Z5FVaG.png

CrazyGuy's Minera RPi image is the way to go with the AM Prisma.  Especially if you have more than 1 unit.  I had very little issues with a single Prisma on a BE Controller used in conjunction with BFG proxy.  As soon as I added my 2nd Prisma - I had nothing but issues. 2 units wouldn't hash for more than 1hr - 1hr15min, had a hashboard that refused to hash 90% of the time.  The only way I could get 2 units to hash half way reliably was to run the 2nd unit with 3 hashboards - the other hashboard would cause the BE Controller to "freakout". Even with running 7 hashboards - I still experienced wide variations in the poolside hashrate.

This morning I moved the 7 board setup to CG's Minera RPi. Started hashing great; poolside hashrate very solid & consistent (still varies a bit but nowhere like it did on the BE Controller).  Efficiency/Reject rate has dropped from 6.25% + to less than 4.15%.

When I got home this evening I connected the 8th hashboard, after a little over 2.5hrs the unit stopped hashing - 1 indicator poolside was a drop in work difficulty (same reflected by cgminer and when on BE Controller); had seen this before with the BE Controller - the controller & Minera both still showed normal poolside hashrate - but the pool showed the unit dropping down to 0 hashrate. But this time Minera Acepted/Rejected/Errors graph showed the drop also (not sure why it still reflected the poolside hashrate).

What I did to get around this on the BE Controller was to use a pool port set for difficutly 2048 (for S4), doing this seemed to correct this issue with BE Controller, and now also with the Minera RPi.  It's like the Prisma doesn't handle vardif very well when more than 1 unit.

Since changing to a fixed difficulty the 8 boards have been hashing for over 4hr40min






http://i.imgur.com/wN1PfEr.png

I am pretty Minera image should work; as long as it has the latest CGMiner -  the newest CGMiner has Prisma support included - no need for the special AM fork.
I am using mine with BE Controller thru BFGMiner proxy & using Awesome Miner for monitoring.  Getting graphs from MRR...
Waiting on usb-uart so I can get it going with RPi w/ Minera

I'm reusing the 750s  that were powering my BTC Gardens - at the time they were quite a bit cheaper that going with a 1300W.

Doing the same with mine; 2 x EVGA G2 750W PSU work great.

got my controller running thru bfgminer proxy with no problem.  currently pointed to MRR, have successfully used with BAN & Slush pools.  Clock @ 250Mhz - Avg = 1.51 TH/s in BFGMiner - pool side graphs are a bit crazy due to the duplicate share issues - normally around 1.40-1.52 TH/s

2 x EVGA G2 750W PSUs work great & are quite a bit cheaper than going a 1 psu route...

After approx 13 hrs of hashing - killawatt bouncing around 1185-1197W.

I have 5 EVGA G2 850W units powering 10 S3/S3+ no problems; no need to use paperclip to short the pin on the motherboard connector either - the PSUs come with a adapter that will short the pins. You only need to use 2 PCIE power cables per S3 - no need to use 4 per miner.

Also using EVGA G2 750W units to power AM Prisma (2 per Prisma)

If you happen to be in USA; Amazon has the best prices on the EVGA G2s and their MiR will cover up to 2 PSUs.

I have used the Dell 750W Server PSUs w/ breakbout boards; they get pretty hot; even with the fan turned up.  I sold 2 of tyhem on eBay - kept 2 for spares; so I could setup miners in my office before they go to mining room in basement.

Happy to report that this setup is working very nice; seeing around 1445-1460GH/s pulling 1195-1205W at the wall.

The Prisma had shifted a bit inside the foam padding, had 2 handles slightly bent (no damage to the boards) that had to be straightened a bit to be able to plug in the power connectors, the fan screws were loose & a screw was missing opposite side of the fan (found it in the box under the foam padding). Miner up and running within 15 minutes of USPS delivering the box.

Extremely pleased; thanks for organizing the GB CrazyGuy!

The EVGA G2 750W has a single 12V rail.

I'm planning on using 2 x EVGA G2 750Watt PSU per Prisma miner; the 750W has 4 PCIE connectors - so 2 per hashboard isn't a problem.

If anyone is looking for a good deal Amazon has the best price currently; plus their MiR is good for 2 PSUs.

There will be 1 USB adatper per Prisma unit - not 1 per blade, correct?
If I plan to run 3-4 Prisma off a single RPi all is needed is a powered USB hub?