Maximum Safe Temp For 24/7

[Ben90]

Hey guys; hopefully this wasnt answered elsewhere but after using the search function (and even more so cuz AT is being really slow for me right now) i wasnt able to find anything so in your guys' infinite wisdom i have a question:

I know that there are a lot of bonuses to keeping temps low; but im a cheap bastard (and like to experiment kinda at the same time) so im sticking with the stock intel heatsink on a i7 920.

I can hit 4ghz @ 1.215vcore; but temps are fairly beastly about 25+ Distance to TJmax under reasonable load, ive been running that for 24/7 a few months but i was wondering what your guys' opinion is on the max safe temps for 24/7/365.

Ive heard stuff from both extremes: Its impossible to burn up a modern cpu with throttling on heat alone; and anything over 60*C drastically reduces the life of a cpu....Im sure the answer will prolly lie somewhere within there, but i think if someone with a lot of experience in transistors/this stuff had a solid argument that u cant burn up a modern cpu, that would be pretty tight...

Oh yea one last thing lol; ive heard that nehalem can take temps better than core2... so if we could get some kinda smackdown on that theory as well

 

[Idontcare]

Anything below TJmax is fine if you don't mind your CPU's expected lifetime to be "on the other side" of the 3yr warranty period. (meaning 3.1yrs or some such)

The QA engineering that goes into the process development itself is all geared towards ensuring this much just from a minimization of extenuating liabilities standpoint to Intel's books.

There is no single temperature threshold above which your cpu's lifetime suddenly diminishes. It is a continuous function that is dependent on an exponential of the operating temperature thanks to the physics that underlie the Arrhenius equation.

As a rule of thumb, for every 10C higher your operating temps the expected lifetime of your CPU is reduced by 50% (think of half-life). Whatever your expected cpu lifetime is if operating at 50C, call it X years, you can expect that lifetime to be cut in half if you operate your cpu at 60C, so X/2 years, and again cut in half once more if you operate it at 70C, so X/4 years, etc.

That may sound dire but understand the lifetime is engineered into the IC from the "top-down" in terms of the thermal specs. Meaning your thermal spec was set for your chip with the desire to minimize the number of in-field fails that would occur under warranty.

So making the assumption that your CPU has an expected lifespan equal to (really we should assume greater than as Intel would not be silly enough to make the mean of the distribution equal to their warranty period and then have to deal with the entire left-hand side of the distribution failing under warranty) the standard warranty period (3yrs) when operating at TJmax is a reasonable assumption. Then for every 10C below TJmax you operate the chip you should double the expected lifespan.

If TJmax is 90C and you operate at 80C then a very reasonable lower-estimate of your CPU's expected lifespan would be 6yrs (2 x 3yrs warranty period). If you operate at 70C then 2x2x3yrs = 12yrs expected lifespan.

What is the basis for my arguing this? At TI we required our process technology to be developed so as to enable the minimum lifetime requirement of 10yrs operating at max spec'ed operating voltage and max spec'ed operating temps in continuous 24/7 operation. It is SOP for the industry.

Now where you can really cook your goose (cpu) is over-volting and running hot. It doesn't take much to be operating your CPU in a voltage/temperature regime that in combination the two factors contribute to lowering the expected lifespan of your CPU to something <1yr.

Not too mention there is always a distribution to the lifespan and your particular chip could have some intrinsic weakness/flaw in it that puts its expected lifespan at a value below the mean of the distribution and by operating at elevated temps and volts it is destined to fail substantially sooner than the warranty period. (I killed my QX6700 in something like 18 months, never operated above TJmax or above Vccmax, but had lapped the IHS so no warranty replacement for me)

 

[Ben90]

Thank you very much for your detailed response; pretty much cleared up any other questions i had

I vote to change ur status "elite member" to forum hero lol

 

[Idontcare]

You're welcome but I'm no one special, there are hundreds if not thousands of people who do this stuff for a living and any one of them would/could have told you the same thing. I just happen to have been lucky enough to have done the things I got to do and am simply yet another forum member here willing to share what I know when it is relevant to the topic. If it helped you then my job is done, if it helps others who lurk/read the thread then that's just gravy.

 

[aigomorla]

Why is it when you say "every 10C u lower your temp you effectively double the life of the processor".. and you get a thank you..

While when i say it, i get a "SHINNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNSSSSSSSS that is soooo BS, which butt are you pulling that number from... yada yada yada.. "


Does it have to do with that long windy explanation? Maybe i should copy this explanation and paste it from now on.

Typically over 70C for prolong operation most of us will say its no good.

70C we'll say ur on the gray line.

Tad Under 70C we call it Safe Zone.

Under 60C we call it being jealous, or bragging rights. :X

 

[GLeeM]

:wine: <---- That's filled with gravy.

Thanks

 

[Idontcare]

Originally posted by: aigomorla
Does it have to do with that long windy explanation?

:laugh: :laugh: :laugh: :laugh:

You've been missed around here aigo, I take it something IRL has been occupying more of your otherwise free time as of late?

Originally posted by: GLeeM
:wine: <---- That's filled with gravy.

For some reason I had to fight the urge to hurl just a little from the thought of drinking gravy straight from a wine glass...I see I'm gonna have to rethink my choice of idioms in the future cheers

 

[Lemon law]

Maybe I am wrong here but differing cpu's probably differ in terms of their ability to keep living under conditions of high heat. After all, both AMD and Intel publish a red line where cpu life diminishes for their cpu's. In general, Intel seems to say 63.1 C is that max safe temp with 65 NM fabs, and its 74.1 C with the 45NM fabs. Or will we buy into the line that Intel and AMD just pick random numbers out of the air to publish? As for AMD, I checked on one of their chips yesterday and they published 74C for that one selected example. And the other variable is that high cpu heat can also damage the motherboard.

And vcore voltage may be another variable.

 

[GLeeM]

:wine: <--- That's a gravy boat filled with gravy

gimme a break, there weren't no plate of mashed potatoes emoticon!

 

[Idontcare]

Now we're talking

 

[OVerLoRDI]

Under 60C is bragging rights now? Wow, where have I been, I guess quad cores really do heat things up.