I7-2600k w/stoch HSF will run much hotter in bios that after windows loads. Reason is that while in bios the CPU spedd will be higher. After windows load you should see the temp drop (Cpu will be around 1.6 GHz @ idle.
That said - Your temps are higher than normal. Most complain about temps for the I5-2500K being around 60->65C. I7 should be a little higher, maybe a ma of 65->70C.
I would check to insure that the HSF is mounted properly. A common problem with the crappy stock HSF is that the puch pins are not fully seated. Need to verfy that the 4 white nubs are proturding (Back side of MB). If you have not watched the instalation video, I recommend watching.
Site Comment - While the Stock HSF works (Barely) at stock it is at the BOTTOM of the todum pole for performance. I do NOT even pull it out of the box, I leave it in to weigh the box down so it does not blow away. For price, Hyper 212+ (Not my choice, but highly recommended here at Tom's and it has a good price/performance ratio. It is OK for a modost OC. Hor OC above 4.5 recommend a Higher end HSF.
Added: Download HWMonitor and prime 95. Run them both while WATCHING your temp. @ stock prime95 is overkill, but I recommend running it for at least 4 ->8 hours on a new build to verify everything is stable. Problem is that you MUST monitor the temps closely for the first 15 Mins, if tmeps look OK then you can go watch TV and check back periodically.