[QUOTE=Luis;386144]Hello Dana, I saw you have got this cpu overclocked at 4.3GHz and I'd like to overclock my 4700K too. Luckily or unluckily I'm from South Italy, so now max temps are 78°C under Noctua NH-L12 cooling (on summer 87°C). What's your heatsink? Temps?[/QUOTE]

4.2GHz 3930K, Corsair H100 extreme. CM HAF XM case, running at ~65C under load
4.3GHz 4770K, Corsair H100i extreme, BitFenix Prodigy case, running at ~57C under load
My son's 3.7GHz 4770K, Noctua NH-U12S, cheap Antec 300 case, running about 57C under load
My Windows 4.2GHz 3770K, Corsair H100 extreme, CM HAF 932 case, running about 67C under load

This summer when we had record high temps for a week and we had no air conditioning saw my first thermal throttling on the 3930K. Fixed by moving it out from under the desk, turning the radiator fan speed from low to medium (I should have done that earlier but I like things quiet), and getting a small room fan to get a little air movement in my office corner. I suppose now that the crazy ambient temps are gone I can turn the CPU fans down again. I've never had issues like that before, but then I've never had a house that hot. When overclocking I try to keep continuous temps using prime95 or intel burn test to under 70C, which gives quite a bit of room with other programs and temp peaks. It also keeps the power draw reasonable.

I've been happy lately with the AIO water coolers, though I worry a little about their long-term life. There are better ones than the Corsairs, but the H100's fit easily, work pretty well, and are frequently on sale. For air coolers I really like the Noctuas, partly because they put so much thought into installation (I had some Scythe tower coolers that worked ok but were the devil's invention for installation, requiring a blood sacrifice from my hands to get them in or out). Noctua isn't cheap though. Nor are the Seasonic power supplies but I won't use anything else any more.

Add: sdbardwick, thanks for the 5820K results! That looks very nice!

Thank you for your feedback. I supposed I should improve my cooling system to enter the overclocking world. Anyway I'm not so insane to run P95 16 hours per day at 78°C. I set turbo boost off so that my 4770K reaches only 66-67°C under load. My case is not very good (Thermaltake Urban S21), but I have got some Enermax Magma Advance too.

I'm curious to run 4770K @ 4.5GHz with DD3 memory 2400MHz, large case and dual fan liquid cooler. :)

@sdbardwick: :bow:

[QUOTE=axn;386236]How come FMA3 is using 18M FFT while plain AVX is using 19200K? By what black magic is FMA improving calculation precision?![/QUOTE]

As George noted (in response to my question about this) earlier in this thread, 18M FFT is fine for low-100M exponents (my code allows up to around 337M at this length, his is probably very similar), but due to some as-yet-unknown cache/memory-performance quirk Prime95 happens to run faster at the larger FFT length ... but apparently only in non-FMA mode using AVX. Thus if the code is using 18M in AVX+FMA mode it must be because his timings indicate that length is faster using FMA.

Note: Use of FMA does generally boost accuracy a smidge, but nowhere near that kind of level.

[QUOTE=Luis;386316]Anyway I'm not so insane to run P95 16 hours per day at 78°C. I set turbo boost off so that my 4770K reaches only 66-67°C under load. My case is not very good (Thermaltake Urban S21), but I have got some Enermax Magma Advance too.

I'm curious to run 4770K @ 4.5GHz with DD3 memory 2400MHz, large case and dual fan liquid cooler. :)

@sdbardwick: :bow:[/QUOTE]

Is 78 too hot to continually run an i7 CPU?

[QUOTE=Primeinator;386344]Is 78 too hot to continually run an i7 CPU?[/QUOTE]
78[COLOR="seagreen"]K [/COLOR]? or 78 [COLOR="seagreen"]°F[/COLOR] ? or 78 [COLOR="SeaGreen"]°R [/COLOR]? or 78 [COLOR="seagreen"]°De[/COLOR] ? or 78 [COLOR="Red"]°Ré[/COLOR] ? or 78 [COLOR="red"]°Rø[/COLOR] ? or 78 [COLOR="red"]°N[/COLOR] ? or 78 [COLOR="Black"]°C[/COLOR] ?
Those in green are ok to run at, those in red are not good, the one in black.....

[QUOTE=Uncwilly;386359]78[COLOR="seagreen"]K [/COLOR]? or 78 [COLOR="seagreen"]°F[/COLOR] ? or 78 [COLOR="SeaGreen"]°R [/COLOR]? or 78 [COLOR="seagreen"]°De[/COLOR] ? or 78 [COLOR="Red"]°Ré[/COLOR] ? or 78 [COLOR="red"]°Rø[/COLOR] ? or 78 [COLOR="red"]°N[/COLOR] ? or 78 [COLOR="Black"]°C[/COLOR] ?
Those in green are ok to run at, those in red are not good, the one in black.....[/QUOTE]

Celsius. Sorry, I was lazy when typing my question.

A better question- what temperature is advisable for an i7 when it is being used nearly constantly?

[QUOTE=Primeinator;386361]
A better question- what temperature is advisable for an i7 when it is being used nearly constantly?[/QUOTE]

Generally, for most Intel CPUs in the last 5-10 years, 85-90C is around the danger line, though CPUs have been known to run fine at 95C. At any rate, even if they work for a year or more, their lifetime is reduced, likely severely.

Below 80C is probably fine, with perhaps fairly minimal lifetime issues; 5 years at continuous 100% should be doable at 75C. Below 70C is good, and below 60C is great.

These numbers apply with some fudge to AMD CPUs and even GPUs. Nvidia cards have been known to operate pretty much okay up to 90-95C, even for CUDALucas. It's been a number of years since I've thought about or used AMD CPUs; I believe their tolerance is perhaps 5-10C lower than Intels, but don't quote me on that. You'd get a better response on dedicated hardware forums.

What Dubslow said matches my thoughts. Some of my reasons for not setting my overclocks very high: I don't continually monitor the CPU temps of all my machines (especially those that are my family member's but still run things like BOINC); the machines gather dust and slowly decrease cooling efficiency until their next cleaning; the ambient temps may rise vs. what they were while setting up; I don't like what I see from the power/temp vs. performance curves at the high end (that is, there's a big chunk of overclocking that is almost free, then there is a knee in the curve and that last bit costs a lot in terms of power and heat). I'm trying to mostly pick up the "almost free" portion rather than push anything very far. A lot of overclocking guides and comments (not on this forum!) are from gamers who don't mind if some FP result is wrong once a day and their machine reboots from instability once every two weeks, not to mention the power draw from their two overclocked GPUs dwarfs the CPU. They may also not have to pay their own power bill for a continuously on machine :).

I've also thought about the merits of EC2 spot pricing (about US $200/month for a c3.8xlarge: 32 core 60 GB) vs. buying a machine and paying for my own electricity. Then I wouldn't have to worry about power costs, overclocking amounts, when newegg has sales, where to put it, UPS setups, etc.

Speaking of heat and components, there's also power supply heat to deal with. I recently had a problem with my machine suddenly powering off and being unstable. It turned out the dust filter below the intake had become clogged. I'm running that power supply at about 85% of capacity, so the airflow is critical.

[QUOTE=ewmayer;386341]As George noted (in response to my question about this) earlier in this thread, 18M FFT is fine for low-100M exponents (my code allows up to around 337M at this length, his is probably very similar), but due to some as-yet-unknown cache/memory-performance quirk Prime95 happens to run faster at the larger FFT length ... but apparently only in non-FMA mode using AVX. Thus if the code is using 18M in AVX+FMA mode it must be because his timings indicate that length is faster using FMA.

Note: Use of FMA does generally boost accuracy a smidge, but nowhere near that kind of level.[/QUOTE]

:doh!: I see that posts 114 & 115 addressed this. I wonder though whether this holds true for just the single threaded case or for all multi-threaded versions as well. Time for some tests!

[QUOTE=Uncwilly;386359]78[COLOR="seagreen"]K [/COLOR]? or 78 [COLOR="seagreen"]°F[/COLOR] ? or 78 [COLOR="SeaGreen"]°R [/COLOR]? or 78 [COLOR="seagreen"]°De[/COLOR] ? or 78 [COLOR="Red"]°Ré[/COLOR] ? or 78 [COLOR="red"]°Rø[/COLOR] ? or 78 [COLOR="red"]°N[/COLOR] ? or 78 [COLOR="Black"]°C[/COLOR] ?
Those in green are ok to run at, those in red are not good, the one in black.....[/QUOTE]

78 degrees Rankine is certainly NOT a good temperature to be running a CPU. You won't destroy it instantly, but most CPU's will not boot at that temperature and some will crash. Over an extended period, if you got it that cold, you would probably shred down the life expectancy much faster than at 78 Celsius.