My EVGA 750ti SC has been super stable. I've only had it for 3 weeks though. I haven't had a crash on it in a while. I've only used it on the ccminer/cudaminer Scrypt, Heavy, Jackpot, Malj, & Quark algo's. I'm running on win 7, 64bit, with settings of +89, +500. Card is installed directly on the PCI slot, I also use card to power the monitor and use that computer for doing MS Office documents and such.
When I'm mining with latest CCminer release (and all previous...) on my EVGA 750TI SC, its core frequency randomly drops to around 500Mhz, and nothing, except for a reboot, fixes this. It does this for every algo, after about half an hour. After that, I can't get any accepted going through. It's mining keccak flawlessly, so I'm leaving it at a MAX pool. But I love how its hashrate for, ea, quark is better than an R9 290
EDIT: No problems at all for my gtx760, no other cards ATM (Gigabyte 750TI is in shipment
)
I have a similar problem with my EVGA 750TI SC as well, but it only happens with quark as far as I've noticed - all of a sudden, low hash/clock, and no accepted shares.
I don't reboot though. If you're on windows, just go into device manager, disable, then re-enable that card. This reloads the drivers, and re-initializes the card. Should work for you as well.
Annoying as heck, though.
It means your overclock is too high. the 500MHz is some failsafe feature where the card goes after a crash
Mine does this even with stock clocks, and slightly underclocked. No problems with anything else, and can usually run +65/+300
