I have an i5 3570k overclocked to 4.2Ghz on stock (dont shout at me yet)
When im just surfing the net or watching videos its around 28-32 degrees centigrade
When im playing games (such as minecraft, offof the intergrated graphics. soon to get a 670ftw) i average 30-40 degrees c , i hear people go up to the high 70's (although iud rather not push my core that hard on stock).
so whats the safe temperature range for my core? whats the highes it can go to.
On a side note just did intel stress test and my cpu hit 78 at one point (however it mainly went back and forth from high 60's to low 70's)
Between 65-70C is where you want to be at most of the time. If it manages to get a little over that every now and agin its not much of a worry. You can get it into the high 70's but this really wont be good for the CPU in the long run.
@hudson yeah they are pretty good temps, ive heard people get really hight temps on stock usually wonder if its to do with my case fans (nzxt phantom 410)
The case fans might help a little, but they're not going to affect your CPU temps much at all most of the time. I would suggest getting a better cooler if you're going to be overclocking any higher, because you're going to really have to start pumping more voltage if you want to get between 4.4 and 4.6 on an Ivy Bridge CPU, which is going to increase your temperatures pretty drastically. I would never overclock with a stock cooler, but that's just me.
Are you sure your overclock is stable? You usually want to run Prime 95 for at least 12 hours to make sure it's stable. If it crashes or if one of the workers stops, then it's not stable.
78 under 100% is high enough, I think. The watermark for safe running is 80C, but you might want to check the chip's data sheet for that (it has very useful information like Voltage rates, some overclocking done by Intel's staff and how that works .. . etc) I, also, don't think I need to mention that you might want to get the system tested under Prime95 for at least 24 hours. 12 hours work for everyday use and gaming, 24-48 is the general concensus, at least one that I found, in terms of marking a system as completely stable. You might, also, want to try Intel's burn test at max for however many repeats just so that you make very sure.
I would be very very careful when pushing the processor beyond the 4.2GHz mark because, depending on the processor, you might need to start pumping voltage much more than you did so far. The problem with the is obvious; pumping voltage increases temps even more so than increasing the frequency, especially on stock coolers.
As Vortex88 said, case fans can be helpful. What I would recommend is that you stress the system without the side panels for an hour or so. Then, let it cool off, put the panels on and stress again. What you want to compare are the temperatures at each case. If you see an unreasonable increase in temperatures, you have to add some fans or fix the orientation of existing ones to maximize the freshness of the air coming at the CPU (Not sure what case you're using, but you might want to pull in as much air as possible from the front and from the side then let it exit from the back and, if possible, from the top)
Of course, you can try and spend some money on an aftermarket cooler for your CPU to run at comfortable temps.