Asus R9 290 / 290X PCB design questions?

[gupsterg]

I was wondering if someone can give some insight on the PCB design of the Asus DirectCU II R9 290 / 290X.

i) location of VRM 1 & 2 temperature sensors

ii) in below image is red box VRM 1 and green box VRM 2

[gupsterg]

I was wondering if someone can confirm this is true?

We noticed a readout at 119c when running Furmark. We never include Furmark results as ‘real world’ indicators however and when gaming this temperature dropped to 110c.

We spoke to ASUS about this just before going to publication and their engineering team said that the placement of the VRM sensor is in a different location on their 290’s, but the VRM’s are being cooled well within specifications.

Image and above quote from KitGuru Review of Asus R9 290 DCII

[elesde]

Yep those temps are what you can expect on most R9 290 models, the DC2 does a little worse on the VRM cooling side than others though.

The VRMs should be rated for 125°C so they are within specs, if that is good for long term reliability is another question 😄

Hardware.fr has some nice IR images as well btw:

http://www.hardware.fr/articles/923-7/asus-radeon-r9-290x-directcu-ii-oc-test.html
http://www.hardware.fr/articles/923-18/thermographie-infrarouge-cartes-graphiques.html

A more in depth analysis of the VRM stages:
http://lab501.net/clash-titans-vga-2014-asus-geforce-gtx-780-ti-directcu-ii-vs-asus-radeon-r9-290x-d...

[gupsterg]

Thank you very much for the Lab501 review it was very interesting to read 🙂 . I liked very much what the reviewer did and think more reviews should have such data 😉 .

TBH VRM 1 is not my main concern, VRM 2 without any heatsink does seem like a glaring over sight. Main point of thread was to get an official line on the VRM1 sensor location though 🙂 .

Looking at these PDF's M3052 & M3058 it shows Tj 150c . If I've understood what I've read about mosfets their efficiency / power output drops with heat but if they are rated so high then even temps of 75-90c on VRM1 shouldn't be an issue?

Below is zoomed image of the VRM1 , also mentioned as PLL VRM in some things I read.

[elesde]

An official word about the location of the sensors would be welcome indeed 🙂

The mosfets usually drop in efficiency with higher temperatures as you said, in turn they produce more heat which leads to even higher temps and so on. Most datasheets I've seen state about 125° as safe upper operating margin even when absolute maximum ratings are 150°.
In the end 75-90°C long term should not be a problem, otherwise most cards would die on a regular basis. It just seems a little high for me too especially when the whole PCB is close to 100° all the time. Long time ago in school we learned that semiconductors degrade faster with higher temperatures, question is if it goes from 100 years to 20 or from 20 to 2-3^^