Topic: GekkoScience has a new pod miner, just in time for Christmas - page 8. (Read 6703 times)

Each Core in each chip is calculating shares.  The total hash rate increases the chances of finding a share that meets or exceeds current difficulty.

New question: Number of chip in miner vs total hash power.
In R909 there are 6 BM1397 chips, so does each chip individually participate in calculating the best share at the same time or the total hash power is used everytime to do the calculation.

WU:4970/Suggest-diff:500=9.94 shares per minute.

Thanks making sense now.
How did you calculate diff of 500 equate to 9.94 shares per minute?

Setting your share difficulty has no bearing on your chances of finding a block or generating a better best share.

It's simply a filter used to keep from swamping a pool with diff 1 shares.  Using a higher share difficulty only filters out low diff shares to decrease the amount of pool resources needed to evaluate your shares and decreases the network bandwidth required to submit shares.

In your example of suggest-diff of 500, shares below a diff of 500 are not submitted and shares 500 and above are submitted.

Your share submission of 9.94 shares per minute just means your hashrate estimate by the pool will have more variance than the pools adjusting to 18 shares per minute.  If you remove the suggest-diff then ck solo will adjust for 18 share per minute which would be a difficulty of around 276.

What i observed is if I set difficulty too high then no of accepted shares per minute is less compared to the low difficulty setting. So I guess higher the accepted shares per minute mean more chances of calculating/generating best share.
So now I have set difficulty to 1 on both units so that the pool adjust the difficulty to whatever is feasible for the pool, that way I maximize my chances of calculation done per minute by each units.
I may be totaly wrong in my assumption.

Are you expecting the suggest-diff command to have an effect on the Worker Utility?

In your screen shot it looks like your suggest-diff of 500 is being honored.  So that equates to 9.94 shares per minute being submitted to the pool.

Hm, why do you think the stock fan is stronger? When comparing the specs between the Noctua NF-A8 and the Arctic F8, I see the Noctua better in every discipline. Slightly higher RPM, better airflow and MUCH better static pressure. The latter of which makes it an even better candidate for blowing air into the unit (the original direction).

the pcb is taking the back heat from the asics, they come with no thermal interface on them, only air therefore the heat stays and gets into the pcb/components including asics.

what i usually do is change both up and lower but upper vs what you have are better 20w/k once you lose the bolts the bottom will fall, do 1 at time just be careful of not move them much.

overall that will help the Asics to get cooler same PCB as also power controllers getting hot will lose capacity and cause performance issues, so keeping all as cool as possible pays out in higher room to push hard the asics and stability of other components.

hope makes sense to you.

Pardon my ignorance, I have attached the screen shots of cgminer for both of these units
Compac-f https://imgur.com/Da9dfnc
R909 https://imgur.com/xPDxaDl

I believe the WU tells the diff1 and these are very high compared to 18.

It will start at your suggest diff and then adjust to 18 shares per minute.  It doesn't really matter what you set it to, pools will adjust it automatically.

Pools also now have a minimum diff so that ASIC's won't flood them with diff1 shares.

So then I think its okay to set suggest-diff of 500 for compac-f and 5000 for r909, as pool will takes care of it and adjust it it accordingly. BTW i am using ckpool

Most pools adjust diff to 18 shares per minute regardless of what your suggest diff is.  It is just a suggestion after all.

I have a compac-f getting 348.5 Gh/s and R909 getting 2.457 Th/s
What suggest-diff i should use for these individually.

I saw some calulation suggesting difficulty of 1 per 1 Gh/s / 1.8 and another one suggested  Gh/s * (71 * .05)^2

Any suggestion?

That sounds great! I will try rotating the fan, too then.

For what it's worth, my experiment with a loosely positioned 'exhaust fan' did not last long; 8h in, the hashrate dropped to 2.4Th/s again. I'm not sure why, but my chips perform well, for a few hours and then slowly drop further and further. It must be thermally related.

Just to be clear: the bottom heatsinks just cool the PCB? And by default are bolted on without any thermal interface (pads or anything else)?
I'd like to prevent touching the top heatsinks, since I believe there's a chance to rip a thermal pad if you don't screw the heatsink on perfectly straight, which would then connect grounds and lead to magic smoke.
But bottom heatsinks are a mod I may actually do. I even have 12W/mK 1mm pads here.

What I think can help is make the fan to pull / extract the air use the original as it is stronger than Noctua (Arctic label pointing the PCB will make it to extract --- I checked their specs as I have Noctuas too) and add thermal pads to the bottom heatsinks 1mm @ 13+w/k will have the highest impact in it, those few changes will give you [email protected] stable on a ~120W on stock voltage.

So far with the size and fan type I don't expect any benefit but swapping to exhaust the air vs push inside did a difference (also adding the thermal path to the backplate)... with High CFM/Pressure might help, BUT heatsink design on 909 is not for that type of work, so I doubt.

I will test it so we can see if works but what I decided based on the construction of 909 was to set a stronger pull fan as I see that will be enough... at the end these are 150W tops devices and to make it push-pull cable needs to be routed differently to make the fan on top no "gaps" and create a tunnel at the 909 chassis. Also power consumption won't be great if we add fans and 6k fans pulls a lot of power at full speed. To me is a balance on the lower power possible and the highest hashrate possible, which I just haven't found it yet...

I don't see it worth to change design for push-pull, I would better look for a pipe/type dissipator/heatsink with very close fins like the ones used at server CPUs, that will maximize the airflow that passes. I am trying to find in the market any CPU like heatsink that I can try on it before I convert them to water cool as I have the compactF (just learning if the current air-cooling can get improved, but my end point is water-cooling it as summer is very hot here and air density is quite poor).

But well it is all about learning and experimentation so couple of usd worth it (at least to me).

I am using some alpha cool memory water cooling same as for the Cf to cool them down, I am working on the holders to leverage the 6 bolts and the backplate which is a great add BTW!  so doing some design/testing to assure PCB does not bend. I also ordered some SSD and custom memory watercolors to see if they fit better than the small Alphacool NDXs. 

I will test before I move them to water and share if it improves... for now 650Mhz @ 2.6T for 48hr and heat is well managed by the current design just with the few mods I did. Since the new 1397AI chips I ordered  have not arrived yet for repairs I will stay away from 650+ speeds as I need these for testing.

you both You and Kano had made an amazing product !!! thank you!!

I'm not sure about that myself.
Earlier today I tried 550MHz with the NF-A8 installed and the stock fan placed in front of it, it seemed to make no difference. I remember someone trying this in a different application and they had the same results. Somehow, it was effective on the Futurebit Apollo, though. However that device was exhausting up top, with the fan pulling air through a pretty dense heatsink. So by the time it reached the top, the airspeed was quite slow. Pretty different scenario.

After those experiments, I placed the stock fan in the back, covering roughly half of the back area and set the miner to 700MHz. (I know; not very scientific. I should stick to 550 now, for further experiments).
Anyhow, I'm now seeing 2.6Th/s, something I have never experienced with this miner before.


Let's see if it can keep this up. So far, that's a 4:30h average. I'm also interested to see if the hashrate drops off over the next 24h or if this double fan setup keeps it above 2.5.

I also replaced the stock fan with the Noctua NF-A8 today, and by that time I checked the heatsink screws as well. Almost all have been at least slightly loose and needed some re-tightening.

As a result of both, the unit is now hashing with 2.15TH/s with the undervolt at 550MHz, and the increased airflow helps to save a few more Watts. 

Does push-pull really matter in a system without much flow constriction? My understanding was that helped maintain airflow in an environment with lots of obstruction, like close-packed heatsink fins, but the R909 is pretty open.