Since we're surprised you haven't experienced a shutdown, I have to ask what did you use to measure temps?
Please use CPUID's hardware Monitor (dl from http://forums.tweaktown.com/gigabyte/30530-latest-overclocking-programs-system-info-benchmarking-stability-tools.html) and confirm.
It's odd to have both the gpu and cpu have heat problems, especially in that case.
- Do you have the case in a cabinet or something like that?
If so, the ambient tmeperature will rise over time as the same air is asked to absorb more and morre heat. That can cause a rise in temps even if the cpu cooler, gpu cooler, and case fans are working properly.
- Do you have good airflow through your case? Dust, bad wiring, bad fan etc can cause heat build up.
Quickest way to check is to use known loads (like Furmark Torture Test and Prime95) and run them for a set period of time monitoring temps. Then lay the case on its side, remove the side panel, and rerun the same tests. How do the temps compare?
In short, you need to get the temps down. This may require reseating the cpu cooler, installing an aftermarket cooler (should NOT be necessary on a stock 2600k), and taking the heat removed from the gpu and cpu and get it OUT of the case.
In the interim, return your gpu to stock settings for safety.