bcavnaugh
...update your Bios on the Motherboard, is it the Current Version?
 

Nah, I'm sure it's not, don't remember the last time I updated that.  I'm going to try a few of your previous excellent suggestions and leave bios for last, esp given that the SLI does work with this bios, albeit intermittently.

If they are not listed here My Products  then you may have registered them under a different Account.
You can get also get your Serial Numbers from My Products page as well. But
Make sure you write down the serial numbers from your cards incase you need to request an RAM.
Under Guest RMA you can also see if the Cards have been registered.

karymcfadden

bcavnaugh
...update your Bios on the Motherboard, is it the Current Version?
 

Nah, I'm sure it's not, don't remember the last time I updated that.  I'm going to try a few of your previous excellent suggestions and leave bios for last, esp given that the SLI does work with this bios, albeit intermittently.

"leave bios for last" This Should Be First!

bcavnaugh
"leave bios for last" This Should Be First!

I updated the bios, no diff.  I'll try the other stuff you mentioned, maybe something will work, thanks.

I downloaded DDU from borisbadenov.ru and it stole all my bitcoins!!!
 
Just kidding.  I ran it, installed the latest nv driver, still no love.
 
Tried swapping the power cables around, nothing.  But then, as I said, Sandra sees both cards.
 

Looks like I can get about $150 a pop for the cards on ebay.  What single card NV will beat a GTX 970 SLI setup?  1070?  It's only like $400.  Maybe SLI is for the birds.

Well I guess you are then flocking away. Best of luck with your eBay Sale.

Thanks, I appreciate all your help.  No idea what else to try.  I really suspect it's the mobo, not the cards or the bridge.

You don't have another SLI bridge to test with?
 
And yes, SLI 970s are about as powerful as a 980 Ti/1070.

I have two, tried em both.
 
When the SLI works it works really well, but it hardly ever works.  Sometimes I boot up and it's working, and I try to postpone rebooting as long as possible.