it does as more current will pass as it switches more times per second, so drains more power. these asics gets quite hot at 700-725 mhz the stock fan wont keep up, the 6600 rpm axial fan i set helps a lot to keep them but i see generating the push pull helped me to pull more heat out but i saw no hashrate improvements in my case.

i will test as @sidekick shared, i will now under and over volt it and do push pull with axials so y pass a ton of air to it to avoid having thermal issues and see where do we get

Hey @kano!!!! THANK YOU my code now works so i can test each chip and set temp telemetry on each this is amazing!!!

THANK YOU!!!

yeah so 3.2 was luck and not sustained over time. so mine is 2.8 T highest i got but they were running very cool!!!)

@sidekick what will be the effect on moving the variable resistor on voltage? will it give me higher Hashrate/ or put me into the power cap soon? and will the asic be damaged if all left or all right? or it is safe to play with it?

Ohh now i see why i get flat behavior after 700mhz, the power i am measuring includes the axial fans and my RBPI to get to 725 i push my fans to 70%, i assume these are the extra 20w.

This is what i see:
- 725 not stable at all- got 3.2 for 3 minutes then crashes down to 500Mhz and as it reboots and reboots Hashrate became to 800G but power never came down. Temps on heatsinks were stable at 45 degrees celsius. I set anoush pull using original in front and exhaust acial at 50% the front i put it on tilted position resting on the cables and pushing the air towards the board (i guess at 45 degrees of angle) that caused higher heat efficiency and took the heatsinks to stable 36 degrees celcius BUT 0 effect on stability… and power got to 138 ( the 3 wats i assume got from the added fan). same 3.2 then crash the 800.

-700 push pull stable on 2.7-2.8 i did not saw these going higher than that after 24 hrs, temps stable on 35 degrees the hottest spot. consumption still high 135.

-650 the current i have only pull axial at 2700 rmps silent ops, stable 2.57- 2.6 T @ 114.5w consumption/ 42 Degree celcius at heatsinks /  net that is quite great vs other setups as looks close to 45j/t and the others were like 50.

something is wrong at 725, i have no idiea what to change ( but not sure if changing stock voltage will help) i dont want ro fry them.

so we can say 3.2 is not valid as they crashes after little time… so to me at least not messing up with voltage 2.8 is the top. i am converting to water cooling but as i saw heatsinks on 35 degrees and no improvement i don’t expect it to change, same as i want it to run 24x7 650 will give better efficiency and longevity.

i am on my iphone so cannot paste the cgminer screen but miner.php and looks ugly but here it is at 650, close to 24 hr run.

Date: 17:47:01 29-Jan-2023 UTC+00:00
Computer: cgminer 4.12.1 When: 17:47:01 29-Jan-2023 UTC+00:00 Status: Success Message: 2 ASC(s)
ASC Name ID Enabled Status Temperature MHS av
MHS 5s
MHS 1m
MHS 5m
MHS
0
GSF
0
Y
Alive
1
GSF
1
Y
Alive
Total:
2,573,644.91 3,004,809.31 2,692,198.92 2,618,194.45 2,5!
2,606,626.98 2,414,314.80 2,616,199.07 2,626,635.49 2,6
5,180,271.89 5,419,124.11 5,308,397.99 5,244,829.94 5,2

Nice one!! i used a high CFM Axial fan, it is in some of my postings, i will share my results of my testing just needed to do one more … but those 80mm fans made a lot i can tell full speed kept the heatsinks on 37 Degree Celsius and i was running at 725Mhz 3.2-3.4 T and power was strangely flat to about 140W the issue i saw was more on the asic was not keeping up the frequency. but i can tell got interesting results I will post them.

Thank you @Kano!!! yeah I am aware you are the designer and developer amazing job!!! it is impressive THANK YOU!!

I did take all apart it has pads 20w/mk 0.5mm i replaced with new same specs.

Confirmed also here:
https://bitcointalk.org/index.php?topic=5423227.msg61628663#msg61628663

I will give it a try, if not i will try to call using shell the JAVA Api, just wanted to avoid os calls. THANK YOU!

Hi @Kano, I tired the api and made it work half way, I changed the number on ASIC ID from 0 to 1 to modify the 2nd unit and it responds "ASC 0 set OK", and it set the frequency to all chips on Asia 0 vs. 1, and also using chip lets say 0,chip,0:0 it set all to 0 on ASC 0 vs. only  chip 0. then if I change to 1,chip,0:0 it sets same all to 0 on ASC 0.

this is how I am sending the payload: {"command": "ascset", "parameter": "[{1,chip,0:0}]"} (then I encode it) is this OK? 

initially I did this but sends error, and landed making it partially work with the previous one {"command": "ascset", "parameter": "[{"ID":"1","option":"chip","value":"0:0"}]"}
or for frequency to all {"command": "ascset", "parameter": "[{"ID":"1","option":"freq","value":"0"}]"}

hope you can give me some advise.

The upper are 0.5mm 20w/k. the ones you selected are ok for the back plate, these can be an top plate option as they are 20w/mk and they have different sizes so you can order  0.5 just in case and if you see ok to have both the same type then a 1mm (the pads can be cut with no effort with regular pair of scissors, so 1x0.5 will be enough for 1 unit top plate the two heatsinks, and also will work the same to backplate) :

https://www.amazon.com/Kritical-Thermal-Pads-Conductivity-othermicroelectronic/dp/B0B1ZF7MZ7/ref=sr_1_18?crid=2MYFZWYK4O5F2&keywords=thermal%2Bpath%2B20w%2Fmk%2B0.5&qid=1674689278&sprefix=thermal%2Bpath%2B20w%2Fmk%2B0.5%2Caps%2C152&sr=8-18&th=1

use Kano new miner.php and get into the gekkochip page check if all 6 are reporting, also at stats if your chips are failing to get set in frequency few causes:
Power not enough - you need a 100w as minimum to run these ones, or they are getting very hot let them cool, and try to push with no to little force the top heatsink and see if move, if it does then the heatsink bolts might got losen with shipping

thermal conductivity is impacted due to height of thermal path so, don’t exceed 1mm so still stays in a good small size and then you dont need crazy high conductivity pads 20+ and a 13+ will do a great job, 0.5 can be very thin and can get easily damaged so a .75-1mm to my experience is a good choice and still will effectively conduct heat to the heatsink.

My bad i checked vs the Noctua R8 (the ones i have with me), I didn’t saw you were using the A8, yes that is better to push but still it is weak, it will do better extracting thought but pushing these fans are quite weak.

having it to push and the original and/or other noctua pull will help, but i not sure how effective will be as it wont be in a close setup “tunnel” but i assume it will help to keep them cooler and accelerate the air causing it to cool a bit more.

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.

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 650@2.5-2.6T 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!!

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.

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.

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.

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…