7970 slows down and eventually turns off

[fortif78]

So I'm mining litecoin on a rig comprised of:

-AMD Sempron 145
-Asrock 970 Extreme 4 Mobo
-1300W PSU
-Currently 2 XFX DD 7970's on this board
(not sure if these are the 7970s people have had a lot of issues with, but other rigs I have them in seem to be working fine.)
-Latest Catalyst Drivers & GUIMiner (reaper)

    Anyway, my issue is that I boot up the comp, run guiminer, and everything seems to be working fine. Both cards are pulling ~550 kh/s and accepting all the shares. After a few minutes, the card in slot two begins to slow down its hashing drastically, and then eventually turns off. I'm not sure what issue could be causing this. I'm assuming it has to do with the mobo since one card alone seems to work fine, and other cards swapped in work as well, but as soon as I try a second card on the board I run into this issue.
If anyone has encountered something like this I'd really appreciate feedback, thanks

-fort

[Vigil]

I have this issue when either my card over-heats or my cgminer crashes due to a driver crash. If you have your display card working hard and then ask it to do some display rendering it can crash. It will then slowly run down.

I also found that the top card blows heat onto the second card and overheats it. try to get better airflow. Catalyst CC seems to only display the temperature of one GPU so it may look OK. Although you may be using the CGminer in prompt.

[fortif78]

I'm adjusting the fans using MSI afterburner. Both temps seem to be in a fine temperature range, so I don't think it is an overheating issue. As for the cgminer possibility, I'm actually mining using reaper through guiminer, so I don't think that is it either. :/ thank you for your input though!

[MashRinx]

I would suggest trying different miners, to try to rule that out as a root cause.  I was testing some of my hardware that has been mining BTC stable for a long time with mining LTC and was getting a ton of HW errors, but only on some machines (all similar configurations).  I switched miners and the HW errors went away. 

If you continue to see similar issues across multiple miners, I would also try swapping the two cards so the one that is now primary is secondary. swap power connectors, and any PCI-entenders if you are using them as well. 

If the problem still exists, I would consider RMA'ing the card if you are still within you warranty period.

[biged214]

I have one of those cards and also a gigabyte version and those DD cards run hot! Get as much cooling to it as possible because I notice if I let mine get to warm it starts to slow down and then once it's cooler again then it picks back up, it's doing like a sea-saw effect. I have an external fan blowing straight to it and moved it to a cooler room in the house and it's been doing a lot better, over clocking it also affects the temp very much too. The DD card runs in the 90's where the gigabyte is in the 70's.