CM10 doesn't flash bootloaders. You'll know which bootloaders you're on with your boot screen (I897 or I9000).OK .. I remember being on I9000 and also on GB bootloaders and did not get SoD, but the system was super unstable.
Then I went back to stock Eclair and updated to CM9 and then CM10. I am supe stable, but have SoD in the morning right after I unplug the charger. Then they go away.
The thing is, CM10 has GB and then ICS bootloaders, right? The Bootloader image and kernel image still show AT&T, so I am a little skeptical, but I thought I replaced the bootloaders when upgrading to CM9. Throughts?
In my sig, there's the link for the I9000 BLs if you wanna try them (at your own risk). Although, a couple other things can be checked first: Do you have Deep Idle on? Do you OC?
Also, you can try to up your min Mhz to 200 (from 100).