I had a look at the OC section of the Asrock Rack EPC602D8A manual. The board does offer complete controls of the parameters. As the temperatures were correct, the only explanation for your problem I can think of is that the system is not accepting the saved configuration:
Page 40 (English)
3.3.4 Saving Current Settings as User Defaults
In this option, you are allowed to load and save three user defaults according to your own
Save 1st User Default
Type the name and press [ENTER] to save the changes as the 1st User Default.
Save 2nd User Default
Type the name and press [ENTER] to save the changes as the 2nd User Default.
Save 3rd User Default
Type the name and press [ENTER] to save the changes as the 3rd User Default.
If the configurations were not saved, the system may revert back to the default settings when restarted.
If the ASRock BIOS tuning is not effective: As an experiment, consider trying Intel Extreme Tuning Utility. It is not as refined a solution as there may be some controls: overriding the duration of running over 130W that are not available.
However, XTU was effective on the E5-1680 v2 in an HP z620 workstation that does not offer any native tuning control. I am running the E5-1680 v2 on all cores at 4.1GHz with only slightly elevated temperatures. In Passmark Performance test, the single-thread rating is 2020 at the default settings, but at 4.1GHz all cores it is 2252. ETU can saved multiple profiles also and my plan is to have a 3D modeling profile with as high a one- core setting as possible (4.3GHz?) and the other cores can run at 3.3 or 3.4.
Of course, a careful control of voltages and timings could yield higher clock speeds. The E5-1680 v2 is quoted as running at 4.3GHz, but in my uses, which includes CPU rendering, I don't want any possibility of instability. A single thread rating of 2200 is enough. I may try having one core @4.2 and run the others at 3.7GHz- that kind of thing, but I am quite nervous to simply try higher settings until failure. The problem is that XTU is zu einfach- too easy!
I'm using XTU also on an HP z420 E5-1660 v2 @ 4.2 on one core and 4.0 on the other five +1.625Mv and the Passmark single thread rating is 2324. Ausgezeichnet,..
I would be interested to know how you progress. What is your use of the system?
HP z620_2 (2017): Xeon E5-1680 v2 (8-core@ 4.1GHz) / 64GB DDR3-1866 ECC registered / Quadro P2000 5GB / HP Z Turbo Drive M.2 256GB (Samsung SM951) + Intel 730 480GB + 2X Seagate Constellation ES.3 1TB / ASUS Essence STX sound card / 800W PSU > Windows 7 Prof'l 64-bit > 2X Dell Ultrasharp 27" (2560 X 1440)
Architecture / Industrial Design /Graphic Design