I have an Asrock x58 Extreme that I can overclock to around 3.48ghz (166 x 21 and perhaps a little higher too) with all stock voltages and cooling (except the DRAM voltage manually set to 1.654 per OCZ recommendations/specs). My case has fantastic airflow (partially due to the 250mm 100CFM fan). The system can run Intel Burn Test, Prime95, etc. for days on end without errors, but most of the time when the system tries to resume from hibernate it often fails to boot. When this happens, the motherboard's auto-recover function kicks in which reduces the overclock to stock settings, and the system resumes just fine. Keep in mind that the system has usually been hibernating for quite a while by the time it attempts to resume. Everything else seems to operate perfectly.

Please let me know if anyone else has seen this kind of behavior or if you have some suggestions.

Main Components:
-Asrock x58 Extreme motherboard
-Intel i7 920
-CORSAIR CMPSU-650TX 650W PSU
-OCZ OCZ3P1600LV6GK (RAM 2 gig x 3)
-XFX HD-465X-ZDF2 Radeon HD 4650 Video Card
-OCZ Agility OCZSSD2-1AGT60G 60GB SATA II SSD
-SAMSUNG HD103SJ HDD
-SAMSUNG HD103SJ HDD (currently JBOD)
-Hitachi HDS5C3020ALA632 HDD
-Liteon iHAS524-T98A DVD-RW
-Benq DW1655 DVD-RW
-Kingston FCR-HS219/1 19-in-1 USB 2.0 Card Reader
-1st PC 250mm Clear Cooling Fan, 800 RPM, 100 CFM