Previously I had reported that my x58 board was a poor OCer. I stumbled upon the problem, it was a bad DRAM setting. In auto, the bios was setting the RAM to 7-7-7, which is way out of spec. I changed to correct 9-9-9 timing and reran my OC test. I had already determined that the same components in my other mobo, a giga ud5, passed prime95 up to 21x194 or 4074Mhz CPU clk. For reference, we're talking:
i7 920 batch 3837A728
Patriot viper RAM, 3x2GB
Tuniq Tower 120, 2100 RPM fan, 75F ambient temp
Vcore 1.356V---this is not BIOS or CPUZ, this is measured with a digital VOM while loaded by Prime95
HT disabled

After correcting the DRAM settings and making sure all other multipliers and settings were the same, and the only variable was which mobo I was testing, the winner is......a tie! That's right, both boards passed 21x194, failed on their 21x195 effort. The temps reported by CPUZ were in the 64-68C range during testing on both boards. I still need to do more testing, the CPU I used was not my good one so I'll need to see if my good CPU will equal the clock I got a couple days ago in my giga board.
So now it appears it all comes down to features and what is/isn't broken that's supposed to work. For example, smart fan doesn't seem to work as it is set in BIOS, but it does work in software. Also, vista sleep mode works in both mobos if you call 19 second resume time 'working' considering 5-10 seconds is normal. DFI has the edge here. It doesn't do the 6 seconds reported by EVA2000, but it does 13 seconds to 19 for the giga.