Problem with frequent restarts on 3x7950's

[LouReed]

I am running 3 Sapphire 7950 4L's, and I am getting frequent restarts. Sometimes it will run for hours, and other times it will restart as soon as cgminer starts. I had originally had an 850w psu, but it kept kicking out due to not enough power. I replaced it with a 1000w one, and ever since, I am now getting this issue instead. I lowered intensity to 18, and even down to 16, but it still does it eventually. Any suggestions? I have 8 gb of RAM. The cards are all plugged directly into the mobo, and the temps are in the low to mid 70's.

Any suggestions?

Thanks!!

[Zanatos666]

Mining LTC?  If you are using Windows, maybe try with a fresh installation if its been a while.  If you are mining LTC, make sure you thread concurrency isnt the problem.

[LouReed]

Yes, LTC now, but it does it even on FTC, and CNC as well. It is a fresh Windows, I just built the rig two weeks ago for mining only. What should thread concurrency be set at?

Thanks!

[Zanatos666]

Not quite sure, I have never mined LTC or FTC, but I know some people have problems with stability and this.  Here is something I read a while about about getting up and running with LTC.  Down towards the bottom it talks about thread concurrency and where you should start at, and how to slow step up.

http://cryptocur.com/litecoin/litecoin-ltc-gpu-mining/

[LouReed]

Update

I played around a little bit with concurrency, but no luck. I pulled out one of the gpu's last night and it has been running fine for more than 24 hours on max settings on both cards. I'm getting 625-645 kh/s on both cards. Tonight I tried to add the third card back in, and it only runs for a few minutes and restarts. Sometimes it restarts as soon as I start cgminer. Just wondering if anyone has any other suggestions? Could it be possible that the mobo is bad, or maybe even the psu bad?

Thanks!!!

[Zanatos666]

You can certainly test it. 3 7950's, even at a 1000w PSU might be drawing too much power, depending on the 12v rail and how it handles it.  You might need to step up to 1200w or higher to ensure each card is getting the proper power draw.  Especially in LTC mining where it is more intensive.  Could be the mobo as well.  Since LTC is more reliant on memory than it is GPU power, and the memory gets its power from the PCI-E bus rather than from the power connections (same reason powered risers are needed for LTC but not BTC).