RTX 3080 error: unable to get fan speed and temperature - Unknown Error (15)

[FP91G]

If you can get it fast shipped to you meaning you are buying locally then I would say it would be a good idea to try the new more robust 010S riser.If you buy internationally leave it as even the version 009S should do well.One thing you can do to try and see if the card has not problems,is remove all other cards and put this one alone in the PCIEX 16 slot of the motherboard and if it mines correctly for let's say 2 days then try it alone without any other card through every riser and see what happens,if the same problems happen with all the risers then this card needs the latest one but if it works well with some of the existing ones and only crashes with a few then you have a couple of bad risers.Try this to isolate your problem,I know it takes time and lost amount of money during the 2 days of testing but trust me in the end it will be worth it.

I get your point, I'll tell you what I did. The Gigabyte card let's say card A was continuously mining for 3 months. And GPU B when arrived, since I had no riser so plugged in GPU B and removed GPU A. This way I mined for 2 weeks. No problem so far. Riser arrives, I put card A in riser and B in mobo. After a week or two problem hits. Since then I've tried changing psu cables, changing 1x slot in Mobo for riser communication, swapping card A and B with each other. Problem has not been solved so far. Every time card with riser shows this error. Kindly comment whether my diagnosis can be concluded that riser has some issues.

As per your suggestion, I think I'll go for 010s riser and hope this problem gets solved.

I will tell you from my own experience that such problems arise either because of the power supply, or because of problems in contacts.
To check, you need to have other raisers and check the power supply cables. Also check the 12 volt voltage with a multimeter under load.
If the voltage is below 11.5 volts, then your power supply is bad.
I do not remember (did not find) the model of your power supply.

Thanks. I have ordered a new riser. Meanwhile this is my psu link https://www.antec.com/product/power/hcg-gold850

You have a good power supply, but you still need to learn how to use a multimeter. For this, the cheapest multimeter for 5-7 dollars is suitable, so it's better to buy a multimeter with a built-in speaker, which gives signals when checking the wires (this has nothing to do with your case, but it will come in handy in the future).
You need to measure the voltage on the cable that is connected to power the video card. 6 pin or 8 pin.
Never trust software sensors, always check control parameters with tools.
And I also advise you to buy a wattmeter, it also costs no more than $ 10. You only need one option - consumption at the moment.

[Headsimon]

If you can get it fast shipped to you meaning you are buying locally then I would say it would be a good idea to try the new more robust 010S riser.If you buy internationally leave it as even the version 009S should do well.One thing you can do to try and see if the card has not problems,is remove all other cards and put this one alone in the PCIEX 16 slot of the motherboard and if it mines correctly for let's say 2 days then try it alone without any other card through every riser and see what happens,if the same problems happen with all the risers then this card needs the latest one but if it works well with some of the existing ones and only crashes with a few then you have a couple of bad risers.Try this to isolate your problem,I know it takes time and lost amount of money during the 2 days of testing but trust me in the end it will be worth it.

I get your point, I'll tell you what I did. The Gigabyte card let's say card A was continuously mining for 3 months. And GPU B when arrived, since I had no riser so plugged in GPU B and removed GPU A. This way I mined for 2 weeks. No problem so far. Riser arrives, I put card A in riser and B in mobo. After a week or two problem hits. Since then I've tried changing psu cables, changing 1x slot in Mobo for riser communication, swapping card A and B with each other. Problem has not been solved so far. Every time card with riser shows this error. Kindly comment whether my diagnosis can be concluded that riser has some issues.

As per your suggestion, I think I'll go for 010s riser and hope this problem gets solved.

I will tell you from my own experience that such problems arise either because of the power supply, or because of problems in contacts.
To check, you need to have other raisers and check the power supply cables. Also check the 12 volt voltage with a multimeter under load.
If the voltage is below 11.5 volts, then your power supply is bad.
I do not remember (did not find) the model of your power supply.

Thanks. I have ordered a new riser. Meanwhile this is my psu link https://www.antec.com/product/power/hcg-gold850

You have a good power supply, but you still need to learn how to use a multimeter. For this, the cheapest multimeter for 5-7 dollars is suitable, so it's better to buy a multimeter with a built-in speaker, which gives signals when checking the wires (this has nothing to do with your case, but it will come in handy in the future).
You need to measure the voltage on the cable that is connected to power the video card. 6 pin or 8 pin.
Never trust software sensors, always check control parameters with tools.
And I also advise you to buy a wattmeter, it also costs no more than $ 10. You only need one option - consumption at the moment.

Thanks for your response. For now i have ordered a new riser and waiting for it to arrive. If it solves problem then okay else i will buy a multimeter/wattmeter as you suggested and will let you know.