Ivy Bridge Temperatures - It's Gettin' Hot in Here

Why is Ivy Bridge so hot? Ask that question in any forum currently, and you are likely to receive one of two different popular (but not entirely correct) answers that everyone has been parroting:

  1. “Power density is greater on Ivy Bridge than Sandy Bridge”
  2. “Intel has problems with tri-gate/22nm”

The first answer is correct, but wrong at the same time – power density is greater, but it isn’t what is causing temperatures to be as much as 20 °C higher on Ivy Bridge compared to Sandy Bridge when overclocked. The second answer is jumping to conclusions without sufficient evidence. If you aren’t in the loop, there’s evidence of a considerable temperature difference nearly everywhere you look – we confirmed it by mirroring settings in our Ivy Bridge review, and we have read similar reports in solid testing at Anandtech as well as from other sites.

So why is Ivy Bridge hot?

Intel is using TIM paste between the Integrated Heat Spreader (IHS) and the CPU die on Ivy Bridge chips, instead of fluxless solder.

Ivy Bridge Delidded, showing traditional TIM

Ivy Bridge Delidded, showing traditional TIM (Image courtesy of pt1t.eu)

 

How does TIM paste generally compare with fluxless solder for conducting heat? Heat conductivity can be measured in watts per meter Kelvin. To be technically exact, we would need to know exactly what Intel is using for TIM paste/solder. When I went to Intel and asked, their polite answer may not surprise you – “Secret sauce”!  Given that, we can use some rough approximations. A solder attach could have a heat conductivity in the range of 80 W/mK. A TIM paste could have a heat conductivity in the range of 5 W/mK. That’s your problem right there! Note that these values are not exact, as we don’t know the exact heat conductivity of Intel’s “Secret sauce”. However, these are values representative of solder or TIM paste, and there is a giant gap between how TIM paste and solder perform in regards to conducting heat. They are in different leagues.

Demonstrating the Problem

Most importantly here, if Intel is using TIM paste between the IHS and CPU die, the IHS effectively becomes a heat barrier rather than a heat spreader. Here is a rough diagram of the current heat transfer on Ivy Bridge:

  • CPU Die -> 5 W/mK  TIM -> IHS -> 5 W/mK  TIM -> Heatsink

It would be far more beneficial for temperatures to take a more direct route such as:

  • CPU Die -> 5 W/mK TIM -> Heatsink

Extra heat interfaces are a bad thing, especially when they have relatively low thermal conductivity. On a fundamental level, it doesn’t make much sense to do things this way from the perspective of optimal cooling. However, it could make sense from a die-protection standpoint.

In contrast, a fluxless solder attach like that described in Intel patents was invented for the specific purpose of quickly and effectively radiating heat away from the CPU die. In this situation with a solder that can conduct heat in the range of 80 W/mK and in light of tighter and tighter power densities as Intel continues to shrink its processor die, you can start to  see on a fundamental level how quickly getting the heat from a very small area to a slightly larger area may be helped by the design of a soldered IHS. This still leaves the problem of a 5 W/mK TIM paste interface between IHS and heatsink, but before you get there you have a high conductivity solder attach between die and IHS that radiates the die heat to a larger area.

Ivy Bridge Power Density

Power density likely became a popular answer because Intel has referenced the challenges it presents with process shrinks, and it just makes sense on basic level. Very hot die, smaller area to conduct heat away from. Blaming power density for the heat issues is easy! However, Ivy Bridge has approximately 75% the die size of Sandy Bridge, which is a big difference certainly, but not enough to explain the stark contrast in temperatures obtained by our peers across review sites and the forums. Where Sandy Bridge would often be around the 60 °C range at a 4.5 GHz overclock, Ivy Bridge has been tested to be in the 80-90 °C range.  How can we blame power density for a difference that large? That dog just doesn’t hunt!

In light of this contrast, we can gain further insight as well from what history has taught us. If you’ve been paying attention, we saw similar issues between the E6XXX and E4XXX processor lines. The E6XXX used a solder attach under the IHS and were far easier to keep cool. The E4XXX used a TIM paste under the IHS and ran hot! Those aren’t the only examples, and I’m certain enthusiasts in the community with better memories than myself can lend further supporting evidence from our past experience. Given hindsight, it is hard to explain why Intel would make a return to TIM paste for Ivy Bridge.

Bottom Line

So based on what evidence we could find from our own investigation, as well as what experience has taught us, Ivy Bridge is running hot when overclocked because of TIM paste between the IHS compared to solder attach used on Sandy Bridge. Why Intel made this choice we aren’t yet sure. We also aren’t sure if they will continue using TIM paste on the Ivy Bridge line, or if this will only be seen on the Engineering Samples like the units sent out for review.  However, we’ve put word out again to Intel and are waiting to hear back if they have any further insight or comment to offer. If nothing else, we can hope their reply will again be in good humor… “Secret Sauce” did give us a laugh!

- I.M.O.G.

Tags: , , , ,

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>

Discussion
  1. I don't know I have a new ivy bridge i5 the 3470, And I am using the stock cooler since I had no thermal paste for my silentX. And I notice a major improvement in temps over lynnfield. it idles in the 30's and never gets to 60 under cinibench load. It gets to 58c highest. The i5 750 would get past 80c sometimes.
    Archer0915
    Hey I have been a CPU **** for years! Always had some of each but like a true **** I love the bigger stuff! Bigger numbers that is.


    are you compensating for something archer teehee :escape:
    xander89
    100% correct people seem to have the illusion that companies like intel give a **** about any of their customers. They dont, period, all they see us as is money into their accounts. :thup

    ... Provided AMD thrive one day intel will rue the day they used tim on their chips! or at least i hope so :chair:


    I agree. St*ff brand loyalty. Come on AMD, bring on competition and consumer choice.
    xander89
    100% correct people seem to have the illusion that companies like intel give a **** about any of their customers. They dont, period, all they see us as is money into their accounts. :thup:

    Hey thats corporate companies for you! This is why we need AMD to bring out a kick ass chip that will really push intel into having to get their act together. I would happily defect to amd if the performance was good enough. I think many people would share that sentiment, screw brand loyalty if they cant be assed to keep their customer happy. Provided AMD thrive one day intel will rue the day they used tim on their chips! or at least i hope so :chair:


    Hey I have been a CPU **** for years! Always had some of each but like a true **** I love the bigger stuff! Bigger numbers that is.
    Bobnova
    Not good at all! I'm highly annoyed with them.

    My point is, it's not a mistake on their part. From their point of view it is the correct decision. They lose nothing and make more money.

    They aren't in the business of making people like them, nor in the business of being warm and fuzzy, they're in the business of making as much money as possible for as long as possible.


    100% correct, people seem to have this illusion that companies like intel give a **** about any of their customers. They dont, period, all they see us as is money into their accounts. :thup:

    Hey thats corporate companies for you! This is why we need AMD to bring out a kick ass chip that will really push intel into having to get their act together. I would happily defect to amd if the performance was good enough. I think many people would share that sentiment, screw brand loyalty if they cant be assed to keep their customers happy. Provided AMD thrive one day intel will rue the day they used tim on their chips! or at least i hope so :chair:
    foxbait
    So, greed is good?

    Remind me of the 80's.


    That part of it is called manufacturing! Things have changed over the years and no instead of engineers running things we have MBAs and CPAs that are clueless about much of the product and design making decisions.

    It (IMHO) is less about greed and more about ignorance in the beginning. The greed kicks in when the engineers get fired for protesting.
    Not good at all! I'm highly annoyed with them.

    My point is, it's not a mistake on their part. From their point of view it is the correct decision. They lose nothing and make more money.

    They aren't in the business of making people like them, nor in the business of being warm and fuzzy, they're in the business of making as much money as possible for as long as possible.
    Why though, really?

    What are consumers going to buy as an alternative?

    It's not polite to consumers, but it's a perfectly reasonable decision on their part.

    They won't lose any customers over it and they'll make more money.
    I can understand the logic of using it in the non-K version but using TIM instead of solder in the K version is just very silly and penny-pinching when the consumer is already hit with a premium price but nobbled by temp restrictions. Wake up Intel!
    I've just deleted two pages of this thread because folks, I'm sorry to say we were trolled by former member Giatrakis. The kind members of this forum attempted to help someone and what we got for it was some immature, pathetic excuse for a person just trolling along. Good riddance.
    thideras
    Guys, we get the point. Please stop discussing Giatrakis.


    awwww :rain: *scours the forums to find another thread where he can use the gif*
    Giatrakis
    What are the basics of thermodynamics if you believe this CPU is pinned in vacuum?

    The main review article is more socking they got 90C in the core at 4.9 Ghz running in watter! Nobody can play it calm down is -15 Cfrom the die temperature. Who can argue with Jeremy Vaughan (hokiealumnus) who did the tests? Or the EarthDog that wrote wow and has experience of the hard testing they do in here,examined many gigabyte motherboards.

    This CPU is connected with double layer of copper with the memory, the graphics card and the peripheral controller so we speak about the half the motherboard! They did it to improve the signal, the power but as you can imagine will double the amount of the heat (90 C) that can’t be transferred out of the core from watter block!? This procedure will take some time but as you can imagine the heat is staffed like breaks to your memory, the graphics card and finally will spread out in all the motherboard!

    I figure 1 hour of prime95 custom torture test with minimal FFT size to the size of your processor cache, 1 Gbytes ram and you will feal the “is getting hot in here” that they wrote to the bone.

    Don’t bug me anymore I done with this thread.


    Your wrong



    sorry i think im mushing the horse into the grounf a bit, but then again I've wanted to use that gif for AGES. Seemed like a good time hehe
    A significant amount of heat does leave GPU dies via the solder pads, the area right behind the core on GPUs is usually quite toasty.

    A very significant amount of "cold" leaves the CPU and spreads to the board when we run DIce/LN2 cooling.

    Not as much as goes through the IHS of course, but a good bit.

    Given that it's heat moving either way, I expect the CPU sheds some heat this way too.