You might be thermal throttling if you get shuttdowns, you need to solve this issue first before getting a new cpu. And obviously you need to get into bios to overclock. If you never heavily overclocked with this motherboard i bet its still working fine and the issue is not hardware related and fixable.
Download hwmonitor and hwinfo and look your graphics card and cpu core temperatures when stress tesing , gaming , keep them backround. If you hit crazy values thermal throttling might be the issue. You need to also update your cooler to atleast hyper 212 look it up, dual fan is even better.
Use msinfo32 method to find out what bios version do you have : https://www.online-tech-tips.com/computer-tips/checking-bios-version/
Version 3.40 is the latest for this motherboard and version 3.00 is the first version which supports i7-4790k and 4770k
I would however support the latest 3.40 since it adds pcie compatibility.
Read the manual or find it from asrock site to find out how to flash bios,
i7-2600 is sadly LGA 1155 processor which uses different socket. So you need either i7-4790k or i7-4770k for noticable gains.
OK what about the razen amd 5 2600 or higher ? Will that work?