Title: Hash Rate Drops with 2nd 280x Post by: richmke on March 06, 2014, 11:39:46 PM I have been mining for 2 months with a Gigabyte 280x GV-R928XOC-3GD REV2. I undervolted and got it to mine at 710-730 Khs. I am using an Athlon II X3 processor with a Gigabyte motherboard that has two x16 slots. I have a Antec CP-850 PSU. More than enough power for two cards.
I bought a 2nd GV-R928XOC-3GD REV2, configured it the same, and it also mines at 710-730 Khs when only the one card is mining. If I have both cards mine (two separate instances of cgminer), the hash rate drops to 680-700 Khs for each card (both cards running at 80c). I have two instances because I want the pool to track them as separate miners so I can fine tune each card. Any thoughts on why the per card mining rate drops when both cards are mining? Title: Re: Hash Rate Drops with 2nd 280x Post by: spiderdk on March 06, 2014, 11:55:48 PM cool them.., vrm temps are high?
I get that on a rig almost same as you. Added a cooler near it and problem solved. Also, unplug your monitor, remote connection to get more stable results. Title: Re: Hash Rate Drops with 2nd 280x Post by: phrozenspite on March 06, 2014, 11:57:19 PM I have been mining for 2 months with a Gigabyte 280x GV-R928XOC-3GD REV2. I undervolted and got it to mine at 710-730 Khs. I am using an Athlon II X3 processor with a Gigabyte motherboard that has two x16 slots. I have a Antec CP-850 PSU. More than enough power for two cards. the r9 series are notorious for downclocking themselves in terms of temp, that's about all i can think of. I bought a 2nd GV-R928XOC-3GD REV2, configured it the same, and it also mines at 710-730 Khs when only the one card is mining. If I have both cards mine (two separate instances of cgminer), the hash rate drops to 680-700 Khs for each card (both cards running at 80c). I have two instances because I want the pool to track them as separate miners so I can fine tune each card. Any thoughts on why the per card mining rate drops when both cards are mining? Title: Re: Hash Rate Drops with 2nd 280x Post by: richmke on March 07, 2014, 12:05:47 AM I don't know how to get vrm temps. gpu1 is sitting at 74c but only hashing at 680 Khs.
I did reduce the intensity on gpu0 to drop its temp to 77c with a hash rate of 425 Khs. I am getting an x16 extension so I can lift gpu1 out of the intake airflow of gpu0. At that point, they should both be able to run at full intensity around 75-77c. Right now, if I run gpu0 at full intensity, it will heat up to 90+c while hashing at 700 Khs. Title: Re: Hash Rate Drops with 2nd 280x Post by: spiderdk on March 07, 2014, 12:23:49 AM blow cool air to see if thats your solution, than you thin about something else to cool it properly
Title: Re: Hash Rate Drops with 2nd 280x Post by: Equate on March 07, 2014, 03:14:58 AM This is called as throttling as the new bios of the cards are not good, either you have to flash the bios or to keep the cards below 75 degree.
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