I am neither an expert at these things nor an electrical engineer, so take my opinion on that basis.
1. How are you powering them, i.e what PSU's and are you sharing the PSU's between rigs?
2. Are you connecting the PSU's to the same socket / extension, if so, try to separate them.

Yes it has been checked, and NO it does not lower watts at the wall. EDIT though in theory it should......

What is wrong with a minimum order of 1? Are they trying to be bitmain?

That PSU provides just 432 watts on the two 12v rails. that represents 72% of the rated wattage. If you are OC'ing, that is the reason why it is shutting down, else it probably has a fault EDIT or as has been stated above, the PCI-e connectors are on one rail.
I use a 550 watt server PSU, but that has 44.5 Amps on three 12v rails, giving me 534 watts i.e 97% of the rated wattage on the 12v rails

I am not by any means disputing your results as that would be futile, however if I may point out my experience with S3's, it is very rare that you find any two units hashing the same, even when using similar freq & voltage settings, PSU and connected to the same pool.

In your case however, that you have experienced the same wall of performance after the first hour, and that happening on most of your units, leads me to believe the issue must be local to your setup.

My first instinct was a heat / temperature problem, however, you seem to discount this as a possibility, and that the units run as normal on stock frequencies seems to justify that. I am not completely sold though since I have never run an S3 variant at temps as high as yours. Before the season change and my moving my rigs outside, I had them all running the fans at full pelt, aka blue wire hack, which kept the temps low, and now that the seasons have changed and my rigs reside in the garden, my temps are a lot lower.

My second guess is how you are powering your rigs. Though you appear to have the right PSU's, this may be a cause if you have them all plugged into the same extension lead. They may not trip your circuit, but they will compete for power, especially if you are running them off a 110v circuit.

If you choose to attempt the OC again, I wish you luck, but I think in your instance I have given as much help as I possibly can, bearing in mind I am neither an engineer nor an electrician.

You are right, they must have re-ntroduced them lately ..... and they are NOT cheaper than UPS for the C1, so looks like will be the same for the S5. Bummer! Seems UPS are Bitmain's preffered shipper ...

Bitmain, could you register as a VAT collection point for shipments to the EU? Would be nice to pay my VAT with the order and not have to deal with your preffered shipper's (UPS) archaic tax processing methods!

I mean, these guys did not send me an invoice and neither did they notify me nor offer me the opportunity to pay due VAT until the van driver turned up on my door and asked me for either a cheque (yes a check in this day and age!) or to phone their office so I could pay via card before he could hand over my S3+'s!

Would be nice if Bitmain re-introduced the option to ship via / with EMS - I am sure it will be a lot cheaper than UPS (and obviously DHL). I know they are not as fast as the other behemoths, but we'd be selecting them in that knowledge.

Your avg numbers should be good now ...... Its something I noticed a while back whenever I did a power cycle, but when the system cleanly reboots the numbers are OK. That is a remnant of the initial Oct firmware bugs, and to be honest I'd rather they did not try and fix it as we've seen what they are capable of in terms of fixing minor bugs in their firmware!

^^^
When you upload to postimg.com, get the Direct link, either by copying it to the clipboad or selecting and copying from the box on the left (highlighted below)

I noticed that repeated x's clear when you restart cgminer e.g via the System Start Up tab (which also happens when you Save & Apply settings) - just saying so you can reduce your restart / reboot cycle length.

Been said a lot of times. S3's are the same, but different ..... most of the S3 variants in my stable run best at different settings, and those with the same settings, on the same pool, over the same connection produce differing results! So there goes.

Save your image on the desktop, then go to postimg.com, browse for the saved file & upload it there, copy the direct link, paste it here  and then put the image tag around that link, voilla!

You probably did a power cycle on the rig! Do a warm reboot via SSH and that should clear your avg figures ....

I used to have that issue (and always had to do an SSH reboot after a power cycle). Of late, though, it seems to have been fixed .... all I did once is before I rebooted via SSH, I first went into the System -> Start Up tab and stopped cgminer, then entered reboot in the SSH window. Now the stats are OK after a brutal power cycle .... (but I was called names when I mentioned the stats problem on this forum!)


I did OC one S3+ before I redid the paste which worked OK at 262.5 (which was the only "good" freq I had at the time). I now redo all the S3's I get by, at the very least, putting heat-pads on the chips, so for now all have been "modded" if you like.

OK, I need to catch up on my sleep ..... getting to 2am where I am so I'll pick up from where you got to in a several hours' time.

Its your rig, but I'd try 275/0800 first. Simply enter the voltage, save and apply then do a power cycle.
On pushing them harder if they are going to throttle back without showing any outward sign ..... that is the question.

There, my friend, is the sign you are looking for!

Fan speeds dropping ... unit is getting cooler

That means there are some chips that have gone offline! EDIT: Either that, or the chips are not getting work ..... now you see how that the queue argument was formented in my mind?

On the queue, I'll take ckolivas' word over what I may recall ...

And yes, that is more like a death spiral, too damn right! I'd have expected it to be flashing x's all over + an increase in HW errors at this point, but then again the new binaries support that --bitmain-hwerror option (or such like) that I have never gotten my head around! I think its that time to try the 0800 setting .... I am convinced it is a heat problem your rigs are encountering due to its consistency in drop-off, so reducing the voltage may help (but may need a power cycle, infact I'd say do one even though I do all my tests initially without one).

That's fair enough, if it is falling that quickly into its uptime, and now registering errors, I expect you'll soon enough see x's on chips too, and if that happened would explain the consistent hash-rate drop-off very well ...... temp build-up!

EDIT: You'll probably have a better run with the 0800 setting .... but see this out for now to get a definitive result.

I assume that when your avg hash-rate falls you restart(ed) immediately, so seeing you have no HW errors, could you let it run for at least an hour after that and see whether you get any HW errors and / or x's on the chips?
I also noticed that the 5s hash-rate flactuates whenever a new block is started / a block is about to end, but soon builds up, so that may be something you have to bear in mind (assuming your hash-rate recovers!).

I remember reading somewhere that it is not a good idea to run without a queue, rather have a reduced one to the 2048 one that ships. I run mine with  --queue 1024, so you could possibly try  --queue 512 if you are averse to having a long one. (I am not conversant with the why's of this, so please don't ask!)