This is a highly debatable topic. Many, including the guy who coded/authored the software realtemp will tell you yes those temps are safe. The majority will probably tell you 70c or under is safe for 24/7 operation. So going by that, your most likely around that when not benchmarking.
What are your temps when doing other things like gaming or other cpu intensive apps?
Here's what the author of Realtemp has to say about core temperatures.
"The value stored in each core is called the TJ Target value. According to Intel, that is the minimum value that throttling will begin so I would disagree on a TJMax=85C theory.
I think the actual TJMax on core 0 of the Core i7-920 CPUs is extremely close to 100C and the reported core temperature coming from that core is more accurate than any CPU Intel has produced. Intel took a lot of flak for the crappy 45nm sensors they used on their Core 2 CPUs so decided to spend a few more pennies on the Core i7-900 series and it shows. The newer 32nm sensors are a step backwards.
I disagree with some of the stuff on overclock.net and haven't been there for a while to read any new theories. When you are running a stress testing program like Intel Linpack, the difference between peak core temperature at the hottest spot on the core and case temperature can hit over 25C. It's definitely a lot more than 1C or 2C. The Tcase specification is designed for system builders. The theory is that if you select a computer case and choose some fans and if you design a computer so the Tcase temperature doesn't exceed 67.9C during your test, then a system builder will not have to worry about the peak core temperature hitting the thermal throttling point at 100C very often if at all during normal use. That's all Intel cares about. They design their CPUs to run reliably up to a core temperature of 100C so as long as the core temperature never triggers thermal throttling, the user will have a CPU that performs at the speed that Intel designed it to run at."