What's the Tjmax for a 45nm CPU? - Page 1
Forum section: electronics / beginners

author: sam1275
author_rank: Frequent Contributor
timestamp: June 10, 2017, 05:27:32 pm
content: Hello.I want to know the maximum core temperature for a AMD processor, which is 45nm process.I extensively searched internet, asked several PC forums, even emailed AMD directly, nothing worked.The common believed 70C is not correct, that maybe the case max value.Could anyone help me?Thanks.

author: wraper
author_rank: Unknown
timestamp: June 10, 2017, 05:49:07 pm
content: As vast majority of AMD CPUs has die soldered to the heat spreader, die temperature is almost the same as case temperature. Claiming 45nm process is not useful BTW, it has nothing to do with it.

author: sam1275
author_rank: Frequent Contributor
timestamp: June 10, 2017, 06:07:43 pm
content: Quote from: wraper on June 10, 2017, 05:49:07 pmThanks for replying.The two measured temperature are not even near, and that CPU ran over 90C at junction for a very long time without any problem.I remember someone said Tjmax is lower on a smaller process, but I cannot confirm that.

author: sam1275
author_rank: Frequent Contributor
timestamp: June 10, 2017, 06:20:59 pm
content: I searched some Intel document and found the Tjunction seems do not have much interference with process size, instead they are very different when package change, for example, a i3 2350M have 85C Tjmax on PGA, but 100C on BGA. How do package method influence the max die temperature?

author: wraper
author_rank: Unknown
timestamp: June 10, 2017, 06:32:37 pm
content: EDIT: did not see your last postQuote from: sam1275 on June 10, 2017, 06:07:43 pmThen why 14nm intel 7700k has 100oC tj?QuoteWondering how you measured it? Put thermocouple in between of the heatsink and CPU? Doubt that.QuoteDoes not mean that max temperature was not exceeded, and, most likely, your CPU was throttling.Where is your process max temp correlation?http://www.pantherproducts.co.uk/posts/cpu-maximum-temperatures/

author: shteii01
author_rank: Frequent Contributor
timestamp: June 10, 2017, 08:11:36 pm
content: It depends on specific model.Since your question does not specify the model, it has no answer.

author: TheAmmoniacal
author_rank: Unknown
timestamp: June 10, 2017, 08:50:06 pm
content: Random example, Opteron 6128 has a Tj max of 70 C as you mentioned. Of course they might last a long time far above this.. Not difficult to find this information, there are datasheets for CPUs too.

author: sam1275
author_rank: Frequent Contributor
timestamp: June 11, 2017, 04:47:52 am
content: Quote from: wraper on June 10, 2017, 06:32:37 pmThe BIOS report 2 different temperatures, one is CPU temperature which is lower, another is CPU MOS area which is higher.

author: sam1275
author_rank: Frequent Contributor
timestamp: June 11, 2017, 04:51:05 am
content: Quote from: TheAmmoniacal on June 10, 2017, 08:50:06 pmUnfortunately I cannot find any datasheet for my CPU, some forum also suggest AMD have a poor documentation on processor(Unlike Intel's ARK).

author: exe
author_rank: Unknown
timestamp: June 11, 2017, 08:48:12 am
content: Quote from: sam1275 on June 10, 2017, 06:07:43 pmThat is my intuition as well, although it's not confirmed by any datasheet. Still, it's an absolute maximum rating. I would assume smaller transistors are more prone to the (diffusion?) damage that accumulates over time. In my experience, overclocked and overheated CPUs and videocards tend to degrade (in terms of max freq) or even die after some months of abuse.But, again, I don't have any reliability data and I prefer to keep my processors well below maximum ratings.

author: wraper
author_rank: Unknown
timestamp: June 11, 2017, 08:55:14 am
content: Quote from: sam1275 on June 11, 2017, 04:47:52 amIf there is temperature sensor under the CPU, it does not show any close to real CPU case temperature in the middle of the heatspreader.