Topic: Problem with 1 GPU - hashrate jumps and higher temperature (Read 104 times)

Hi everyone, it's my first post but I've been here a long time. Now I have some problems with my rig and I have no idea what is going on. First GPU behaves strangely. I noticed the problem after adding fourth card, then first GPU started working with apparently higher temperature. All cards have 59*C (the driver probably controls the fan's speed to maintain this temperature), but the first has 67*C. I am mining from two weeks so far, the card is theoretically getting valid shares, but I am worried about hashrate jumps. It should be stable about 27mh/s and here it sometimes drops to even 22mh/s and for a moment, after a while it returns. I suspect that the cause is common for both cases - the hashrate drops and higher temperatures.
My rig: 4 x MSI RX 570 Gaming X 4GB, the first two Hynix memory manufacturer, another two Elpida memories.
Rig goes stable all week without hanging. I am using claymore miner 10.2. with the following settings:
-cvddc 910 -mvddc 910 -cclock 1150 -mclock 1970,1980,1940,2020
(timing differences are because I found the maximum for each cards - the hwinfo shows GPU errors above this timings and now they hold 0 or less than 10 per hour)
Here is screenshot from claymore:
https://cdn.pbrd.co/images/GY3xvJz.png
https://cdn.pbrd.co/images/GY3xOuv.png
What I've tried to do:
- I reduced the memory clock speed
- Increased voltage
- I changed the GPU in places (open frame)
- I uninstalled the AMD driver and reinstalled (using blockchain beta drivers)
No effect.
I do not know what else I can do and what the problem is. I will be grateful for your help in solving the problem.