Is stress testing safe?

Safe oft depends on the manner of usage .... nothing is safe if used irresponsibly. Running Prime 95 and going to sleep or leaving the room might be considered crazy by some but today's CPU's are self throttling and not "supposed to" result in any damage....still it 's something I don't do. I run P95 overnight only after running it for 30 minutes and monitoring temps to be sure they are stable.

That being said, everyone has their own fav set of tools and everyone gets comfy with a set of procedures and tools and uses them accordingly. Prime95 overnight testing is deemed by many to be the only way to test CPU's but when moving up ya OC's in steps, that can lead to a lot of long overnights and leaves a new machine owner waiting days for his PC to be finished.

Personally, I like to use OCCT CPU and GPU tests for my CPU and GPU overclocking. The tests run an hour so I don't have to wait a day between steps, they show voltage and temps so I don't have to load additional programs, they products graphs over time so I can look back w/o sitting there and see if there were any bumps and how often they occurred. The alarm function is nice so if I am working on 2nd or 3rd machine at the same time, reading THG or whatever, my attention is pulled back to the machine in question.

Running OCCT's PSU test should be done only with known quality PSU's.....OCCT's GPU test can kill a cheap PSU.....they are quite up front w/ this warning. I don't use anything w/ < 9.5 jonnyguru performance rating and 90% of the builds get PSU's w/ 10.0 ratings.....those I don't worry about. You won't see me running it on a $35 "store brand".

If I am building for someone, it has to be recognized that the time I spend doing this is going to be limited. When doing a lot of builds however, you tend to settle on a recommended buy list which has perhaps 3 choices of each component. My most common build by far is a 2500k w/ 1 or 2 factory OC'd 560 Ti's. I know from experience that I easily can hit 4.7 - 4.8Ghz with a Silver Arrow....4.5 - 4.6 with a Scythe Mugen 3 with very little effort. I know from experience that I can get the 560 Ti's at 1000Mhz or better, most of the time w/o a voltage tweak. I can dial these in very quickly. Yeah, I'll bet that with a few more hours of tweaking I can do better more than 50% of the time ..... but that takes an investment of T & E (time and effort) that I can afford to invest.....I'll spend up to 2.5 hours, with the new owner, show him what settings can be tweaked, give him some printouts of various OC guides and then take him / her through at least two "steps" on the CPU and GPU.

Step 1 - CPU 4.5 GHz - 56/57/59/56 core temps ..... GPU 960 Mhz - 71 bottom card / 73 top card
Step 2 - CPU 4.7 GHz - 64/65/68/66 core temps ..... GPU 1000 Mhz - 80 bottom card / 82 top card, .

BIOS settings for "stock" .... and the two steps above are saved as separate BIOS profiles so if they experience issues, can always load a lower OC profile . Then they take the machine home and they do the final P95 run to insure long term stability.....they can play with it from there.