Hello,I know this is a little off topic, but this is quite important information for me, because it's about running FSX as good as possible. I have an i7 860 2.8 GHz, and I overclocked it to 4.0 GHz. The temps are really good, about 35-40C. Base clock is 181x21=3801 MHz. All power savers are off. Intel Turbo Boost is on, so it runs at 4 GHz. I left CPU VCore an AUTO, the Voltage is 1.4V. I know this is not a pc forum, but people here know a lot, and on websites like tomshardware.com I don't always get the answers I want, so I thought I'd ask it here.Does this look like a good overclock to you? I'm not having any problems or blue screens nor freezes nor any problems with FSX. But what I'm concerned about, is the stability of the overclock. Everyone is always saying that an overclock has to be stable. But why? Could it damage my hardware if it's not stable? And how do I know if it's stable or not? Any help would be appreciated.Thanks in advance,

First of all Avsim actually does have a hardware forum for just this type of post. Now with regard to your questions, its a very good one. A stable system will result of fewer (or hopefully zero) CTD's when you are doing the stuff on it you overclocked for in the first place (in this case FSX). Now whether it has to be 100% stable when using Prime95 for 24 hours vs. when flying FSX for 8 hours I am not really sure it makes a difference. I did not even run my overclock on Prime for more than 2 hours so for all I know my system is officially unstable. Having said that, I don't get any CTD's when flying FSX for long periods of time so as far as I am concerned its stable. Mark.

Stable overclock = no crashes of any kind + better performanceBad overclock = crashes, fire, destruction, CTD, blue-screen, etc..etc..

A 'stable' overclock would be in my mind defined as no crashes, blue screens or overheat alarms after 5 to 10+ hours of continuous Prime95 (or intel burn test) torture tests. Anything less than that is defined as 'unstable'. A really bad overclock = no BIOS POST. FSX however will never push the CPU that far, even though it is very dependent on CPU resources. You can happily play FSX even if your clock is unstable and fail the torture tests. The key is the good core temperature monitoring, and I do it via my Logitech G15 keyboard LCD screen. Lastly disable turbo boost, load line calibration and hyperthreading.

So stability is kind of like- if you overclock the computer too much and push the chip too far beyond its specifications, it will literally make a mistake like 1+1=3. Depending on exactly where this mistake happens, it might do nothing, or it might cause your computer to reboot. These kinds of errors usually happen under high load, which is why programs like prime95 are used to stress the computer. Sometimes you will see an unstable system where prime95 runs, but computes an incorrect result (which causes the program to stop, and it tells you the calculation was wrong). The point of testing stability with a tool like prime95 or IBT is that if the system is stable under those programs which test maximum load, then you are guaranteed that no program will encounter problems due to overclocking. Real world usage is invariably not as intense. In fact, sometimes you will see people talking about computers being game-stable vs. prime95-stable. If your overclock is unstable, you won't be doing any damage to your hardware (assuming your temperatures and voltages are OK)- it will just be an inconvenience. I suppose you could get file system corruption if your computer keeps powering off necessitating chkdsk or reinstallation of Windows. If your computer doesn't crash and your programs seem to run OK, then you could say your overclock is fine for normal use. But unless you get it to behave normally when running prime95 etc. you might find one day that it crashes when you do something CPU intense like video encoding.

I had an intermitent problem with my PC crashing and rebooting. Cured with extra memory!!!vololiberista

It is much simpler then that. Stable/unstable are not absolutes, they are relative to the job that you need done. If your system needs to do your company's last payroll calculation before christmas, you shouldn't let your neighbours' kid's second best mate overclock it to the max so he can pwn his l33t warez d00dz! Equally an unstable system is simply one you don't trust, whether you know it has crashed doing the job you need done, or just because you are afraid it might crash at a critical time. A system stable enough to run FSX at max settings, or pime95 for 24hours, might still be not stable enough to run a life support system.

Alright, I'll do this test in Prime95. But what I'm afraid for, when I'm torturing my hardware non-stop for 24 hours, that it's gonna wear it down quickly. Could this Prime95 damage my hardware? And btw, when i'm running Prime95, my temps go up to 70C, with FSX it's only 40C. Dunno if 70C is dangerous though...

Instability is a sign that something's going wrong inside the CPU, the RAM or the mobo chipset - either it's getting too hot or it's just past the point where it can reliably operate without raising the voltage more. In some cases there's just going to be a wall that you can't get past - every individual CPU is unique and does have a physical limit for how fast you can push electrons through it... Now, if you can run FSX fine but Prime95 or Intel Burn Test causes errors or blue screens after a while - it's up to you. If FSX is all you use your computer for, then you're probably fine - FSX is never going to push the CPU to 100% maximum load like those test utils do.The only way you're going to actually damage the CPU is if you push it past the thermal design limitations - 70C under max load is nowhere near that. Intel lists around 99C for it.

Instability is a sign that something's going wrong inside the CPU, the RAM or the mobo chipset - either it's getting too hot or it's just past the point where it can reliably operate without raising the voltage more. In some cases there's just going to be a wall that you can't get past - every individual CPU is unique and does have a physical limit for how fast you can push electrons through it... Now, if you can run FSX fine but Prime95 or Intel Burn Test causes errors or blue screens after a while - it's up to you. If FSX is all you use your computer for, then you're probably fine - FSX is never going to push the CPU to 100% maximum load like those test utils do. The only way you're going to actually damage the CPU is if you push it past the thermal design limitations - 70C under max load is nowhere near that. Intel lists around 99C for it.

Adding to what Ryan said about temperatures; FSX won't even push it past 60 on a 4.8 GHZ OC (on he 2600k) and not even crysis will push further than that. Only programs that can push the temperatures at their max are cpu benchmarks and folding progs I'd say that 100 runs of IBT is good enough to determine stability, as it will be stressed to its limit. Also, if you get 70 degs on IBT, you will never ever get 70 on normal use, even if you run 10 FSX windows at once xD

Instability is a sign that something's going wrong inside the CPU, the RAM or the mobo chipset - either it's getting too hot or it's just past the point where it can reliably operate without raising the voltage more. In some cases there's just going to be a wall that you can't get past - every individual CPU is unique and does have a physical limit for how fast you can push electrons through it... Now, if you can run FSX fine but Prime95 or Intel Burn Test causes errors or blue screens after a while - it's up to you. If FSX is all you use your computer for, then you're probably fine - FSX is never going to push the CPU to 100% maximum load like those test utils do.

If Prime95 causes any bluescreens, chances are you'll eventually get one in FSX. Usually at the worst possible time on a long flight.

If Prime95 causes any bluescreens, chances are you'll eventually get one in FSX.  Usually at the worst possible time on a long flight.

Thanks for this. I've always used OCCT and had achieved what I thought was a pretty stable system with a 2600K @ 4.8Ghz. But after one or two CTDs/BSODs with my new PC I thought I'd better try with Prime95 v26.6. It turns out that I don't have anything like a stable overclock: at best, I get a BSOD after just ~1.5 hours on the standard "blend" test! What a pain in the proverbial. I don't have the time to fiddle around with this stuff AND try to complete a flight without fearing a BSOD on short finals.Tim