Topic: GekkoScience has a new pod miner, just in time for Christmas - page 9. (Read 6937 times)

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.

it will help but in reality the way cables are today might need very small fans and to have a proper push-pull setup fans must be similar in cfm and pressure capacities (i tried some noctua 40x25mm and are large to fit) so i ordered som 6k 80mm fans from amazon one 25mm and other that is 38mm but cfm is 3x the current but noise will the the issue with these but i want to test how will it help.

this is the 38mm
https://www.amazon.com/Wathai-Cooling-80mm-Speed-Bearing/dp/B07QX3QCP5
this is the 25mm that fits with mo issues but you need in both an adaptor (link also included)
https://www.amazon.com/GDSTIME-80mm-25mm-Brushless-Cooling/dp/B00N1Y50QQ
the adaptor
https://www.amazon.com/Mainboard-Standard-Extension-Power-Cable/dp/B07Z8Z182S

once i get them netx week let me test it and i can report back so you don’t throw away money … i can try to set a push-pull using the original fans i just need to get some very large bolts/nuts to use the top bolts from the current fan to secure the front ones just i need to do some measuring to avoid bending too much the power and usb cable as i am using an atx 1600w pc psu and the pcie cable doesn’t bend too much.

hope it makes sense to you.

@gergar What do you think about using 2 fans (1x intake, 1x exhaust)? I mean, the downsides of having ports on the back now is that it's not really possible, but maybe a small fan that covers part of the back side could help.
Or using 2 fans in the front. That did wonders on my Apollo.

Yes and i have done that to calculate the expected BTUs etc from the asics, what i found was about a linear growth, 50w per 100Mhz of freq increase and about 10+ degree increase. i am preparing some thermistors to check temps at bottom on art of the heatsink that i assume might be closer to the asics if there is good thermal transfer.

have another question on the Api, i sent via python a post message with command=ascset parameter={0,freq,400} but it returns “Unknown Option: freq” is there any documentation. on the payload to be sent using json? i used the page that explains in summary the api but as it uses | i am not quite clear how will it read using json command/parameter format.

Actually, what matters most is the heat of the BM1397 chips.
If that heat is going away, to other components, then that's good.

One way to measure this is the W usage, since it will go up, at the same frequency, if the chip is heating up.

Hello,

to make easier some definitions first, 550Mhz as i tested with my gekko compactf settings temps in celcius

FP= Top Heatsink (front plate)
PCB
BP = bottom Heatsink (back plate)
EX = exhaust (stock = front / modified = back)

Stock
FP = 43 / with all bolts (50)
PCB = 54 / with all bokts (47)
BP = 27 / with all bolts (30)
EX = 48 / with all bolts (50)

Modified
FP = 53
PCB = 35
BP = 45 (temp at front = 21, two degrees lower then ambient 23)
EX = 44

what it means?, the heat was mostly staying at the PCB as the heatsinks were not fully operational, once i adjusted bolts temp lowered some how but still the lower heatsink was mot doing clean contact with the pcb (air in between. But the air as it was not strong enough to move out stayed there in the front near the cables. with the changes the backplate is draining more heat from the pcb, pcb is colder and top maintained temps so contact issue was the initial problem. Then all front part is about ambient temperature, as air gets higher speed it is 2 to 3 degrees lower just cos pressure changes, and the air going out of the fan and case is hot.

I am running it at 650 now and here the temps i just captured as i was intrigued on how much temp gets from 100Mhz more:
FP= 66 (some are hotter 69-72)
Pcb = 36-37 relative cold
BP= 50 (seems it still gets heat out)
EX = 49 - 52

I assume with current stock fan might get too hot to go higher on freq, not sure the asic temperatures down there but they should be extremely hot. 650 had maintained 24 hrs at 2.6T stable (21 degree temp intake, maybe cooler temps can allow it to go higher on freq. - mine anything higher than 650 starts to bounce back to 650-646 and i get lower hashrates.

my 2 r909 miners have been running for ten days now and the performance at 680 and 640mhz is impressive
both pod miners have settled between 2.34 and 2.45 th/s

It's 96% of expected speed, so not that impressive. Yours is running a little over 80% expected. I bet you could see the same 2.3TH effective from about 600.

That's impressively high for just 550MHz. After a few hours of running 700MHz, mine seems to have settled on around 2.3Th/s, after starting at ~2.5Th/s... Still not sure if this is temp related.

Hello, what was the temperature difference you have measured with your temp camera when the (stock?) fan was blowing out? Would be interesting to know.

Added info from API-README about how to setup a web page to view your gekkos
https://kano.is/gekko.php#mph
Has a Gekko specific page and a GekkoChips page that shows the chips

Edit: Update, I added an extra command to the above steps that I left out before,
since you need to get the latest miner.php with the Gekko updates.

Alright finally just got around to this and ordered 2 of em from BitcoinMerch! 

Looking forward to tinkering with these next week!

Thank you yes i meant thermal pads (20w/k) both sides sorry 😞 . I used .5mm too and 1mm bottom to have symmetrical balance between heatsinks too.

yes maybe springs or locktite on them it was strange but the product is quite great maybe testing only with the outer 4 bolts…

We've recently gotten a few reports of screws rattling loose during shipping and anything that's gone out since then has blue threadlocker on the screws. There's already a version change in planning to improve heatsink screws and ease of getting the case on and off.

It's not advisable to use thermal compound on the top chips or we would have done so. The IC package is plated and electrically connected to local ground, which means that unless there's electrical insulation between the package and heatsink, you can cause shorts and break stuff. We use a 0.5mm 20W/k silicone pad to avoid shorts.

I'll do some testing with adding TIM to the underside heatsink and see how that changes heat management.

Sounds like you need to track down whoever you got them from and get them to explain why they were disassembled.

They are tested mining, properly assembled, before even being sent to the distributors.

Hello all, i want to share my experience and some advise on cooling as i found out points to improve:

I got 4units few weeks ago, all 4 came with bolts off in the case, initially i wasnt clear where they came from i thought they were “spare bolts” 😂, but as i set them and ran for couple of hours at stock frequency 400 i saw the hashrate going down to 1.4T and they went down to zombie no chip… that made me think about temperature issues…

I open each of them, net it is not easy to open but that can be an improvement in future … i found out:
1 both heatsinks were moving missing the bolts i had at the boxes.
2 the fans are pushing the air to the inside vs pulling it out
3 there is no thermal compound on the backplate heatsinks

what i did:
1 put thermal path covering the backplate heatsink (20w/k), used same compound for the top at the BM chips.
2 when bolting it i made a cross then center then cross then center until the bolts were full secured, 6 bolt array needs a sequence to avoid the issue of having some loosen bolts due to the center bolts will cause the outer ones to lose pressure as the heatsink gets tightened.
3 inverted the fan to pull the air, why, the current setu makes hot air stays inside the case (measured with a temp camera)

Results:
550 stable - 2.2T each (48hrs no TH drops) very cold running- i kept them back there for longevity 85w per R909.
600 stable - 2.4T each (48hrs no TH drops) temperature got slightly high, but still looks fine.
650 stable - 2.6T in some / 2.5 in others (48hrs sone git back to 600Mhz) i guess silicon lottery and or needs better heatsink like cpu server with very small fins but many to increase thermal transfer and better fans

As i saw risk of damaging the asics i stop there (i had compact F damaged due to temps, 6 and replaced the asics with new AI but after monitoring i found that thermal will kill the chips so fyi)

I will do the same 750 test and report back just with one and try to measure temps with my temp camera.

hope this helps to improve the thermal protection so far with stock heatsinks these toys performs amazing just make the backplate to really work adding thermal compound on it and you will really use the backplate to remove heat.

I had the same thought when I saw the hashrate increase after the slight undervolt at 550MHz. The avg hashrate is at 2.12Th/s by now, I think I will just leave it running like this for a few days to see if it goes up even further yet.

I had the same experience. With stock voltage, I tried various freq. settings from 500 MHz up to 725 MHz. At the beginning of the run, cgminer reports up to ~2.5 TH, then, after 30min or 1 hour it slowly drops the hash rate.
Currently, at 725 MHz (which seems the maximum, increasing it, the HW errors raising as well to an unacceptable ratio), the miner is dropping down to ~2.190 TH.

Also tried to increase the voltage knob from 12 o'clock to 3 o'clock in small steps, to no avail. So I turned it back to the factory setting.
The next step will be to measure temps and increase airflow if necessary.

Interesting; mine dropped a bit down to 2.1Th/s over the last 6 days. I am still on 675MHz. It started at almost 2.5Th/s. Did anyone else experience such a little bit of drop-off after the first few hours of operation?
My only theory right now is that they get slower as the heat up and the heatsink becomes fully soaked. Not sure about that, though.

https://kano.is/gekko.php#vol