Thinking of OCing my 7970

After reading about how 7970s can easily have their GPU and memory clocks increased using AMD OverDrive at stock voltage I was excited to try it. Then I was disappointed that I couldn't get it above 1050Mhz, when others maxed out the sliders (1125Mhz, and 1575Mhz) without issue. I then read that I might have a bit better results if I switched the card into its second bios, and unfortunately my card has the "1-2" printed on the board but no actual bios switch. Without having the ability to switch back to the stock bios if I mess something up makes me less sure about trying to increase voltage to be able to increase the clocks. Will this card's poor ability (relative to other's) to OC at stock voltage (1.175v) be indicative of poor results at higher voltage? Does anybody have this card OCed at stock voltage or higher? Any input would be appreciated.

The card is an XFX and says FX-797A-TDFC-V5.0

System Configuration:
Chassis Model: Special Deal Hot Seller - Cooler Master 942 HAF X
Exterior Finish: - Standard Factory Finish
Trim Accents: - Standard Factory Finish
Processor: Intel Core i7 3770K 3.50 GHz (Unlocked CPU) (Quad Core)
Motherboard: ASUS P8Z77-V DELUXE (Intel Z77 Chipset) (Higher Overclocks and Unique Wi-Fi Features) <b></b>
System Memory: 16GB DDR3 1600MHz Digital Storm Certified Performance Series (Highly Recommended) (Hand Tested)
Power Supply: 800W Corsair GS (Dual SLI Compatible)
Expansion Bay: Internal Digital Media Card Reader (Black) <b></b>
Hard Drive Set 1: Operating System: 1x (240GB Solid State (By: Corsair) (Model: Neutron GTX Series) (SATA 6Gbps) <b></b>
Set 1 Raid Options: - No Thanks
Hard Drive Set 2: Multimedia\Data: - No Thanks <b></b>
Hard Drive Set 3: Backup\Misc.: - No Thanks
Optical Drive 1: Blu-Ray & DVD Writer/Reader (Burn + Play Blu-Ray & DVDs) (12x BD-R) <b></b>
Optical Drive 2: - No Thanks
Internet Access: High Speed Network Port (Supports High-Speed Cable / DSL / Network Connections)
Video Card(s): 1x AMD Radeon HD 7970 3GB <b></b>
Add-on Card: - No Thanks
Sound Card: Integrated Motherboard Audio
Extreme Cooling: AIR: Stage 2: Noctua NH-D14 SE2011 Extreme Performance <b></b>
H20 Tube Color: - Not Applicable, I do not have a FrostChill or Sub-Zero LCS Cooling System Selected
Chassis Airflow: Standard Factory Chassis Fans
Internal Lighting: - No Thanks
Enhancements: - No Thanks
Chassis Mods: - No Thanks
Noise Reduction: Noise Suppression Package Stage 1 (Optimized Airflow & Fan Speeds Only) <b></b>
LaserMark: - No Thanks
CPU Boost: Stage 2: Overclock CPU 4.5GHz to 4.8GHz (Requires Pro/Deluxe/Sabertooth Motherboard)
Graphics Boost: - No Thanks, Please do not overclock my video card(s)
Memory Boost: - No Thanks, Please do not overclock my memory
OS Boost: - No Thanks, Please do not tweak the services on the operating system
Windows OS: Microsoft Windows 8 (64-Bit Edition) <b></b>