Inside of AC-68U

[netmik3]

1. shirt heatsinks. n66u had 10x more
2. Replacing thermal pads did nothing for me and is wasteful, there is a large gap you have to fill.
3. Heatsinks go through thermal pad > rf shield > ??? > chip
4. Mine is still hot
   2.4 GHz: 51°C - 5 GHz: 54°C - CPU: 86°C
5. I destroyed the back sticker.

https://imgur.com/a/8OZD3

 

[TonyH]

Hi,
On any component 90 deg. C is red flag. Running too hot will decrease the life of component. Here R7000 which replaced AC66U stays much cooler than ASUS one.
I could never understand why they use thermal pad.

 

[bigcid10]

yea ,I'm bailing on this ac68u
temps are 86c
give that 7000 a shot

 

[MaX PL]

i'm not bailing on the ac68u yet, but am purchasing the r7000 today to test.

the 68u will hit 30 days Friday next week and its still up and down as far as 2.4 and 5ghz stability.

 

[Sky1111]

And this is what we pay $200+ for?

Real shame

 

[MaX PL]

yeh i'm def. not rewarding asus for releasing beta products if the r7000 is a champ, and stable throughout the day unlike the ac68u.

i'd have patience and wait for new firmware if this was a $50 router, but if youre gonna price yourself above the competition, you better bring a superior product.

 

[RMerlin]

Before stating "it's too hot", has any of you read the Broadcom specs determining how hot is too hot? How do you know that it's TOO hot? Right now, people are basing decisions on mere opinion, with no factual data. When I asked an engineer who actually works with various Broadcom SoC, he told me that some of these chips were rated for as high as 130C.

I used to have an ATI video card that would hit over 100C under load. The card never had any stability issue, the chip was designed to run that hot.

This is why I was hesitating about adding CPU temperature, and I am considering removing it. Brainslayer had the exact same train of thought with DD-WRT after he added the CPU temperature.

If people are going to get paranoid about temperatures, then I will simply remove them from the webui.

 

[JGrana]

1. shirt heatsinks. n66u had 10x more
2. Replacing thermal pads did nothing for me and is wasteful, there is a large gap you have to fill.
3. Heatsinks go through thermal pad > rf shield > ??? > chip
4. Mine is still hot
   2.4 GHz: 51°C - 5 GHz: 54°C - CPU: 86°C
5. I destroyed the back sticker.

https://imgur.com/a/8OZD3

Netmik - thanks for the photos of the operation (and the pizza). I was going to beef up the heat sinks, but it sounds like a lot of work for marginal gain.
Soooo, I dug up a small fan from a PC case (12V fan) and also found a 9V power adapter. Spliced them together and hung the fan on the back right side of the rear of the case (blowing into the router through the air slots above the USB ports).
I am running overclocked @ 1Ghz and have both radioes set to 100mw. Previous, my CPU temp was hovering around 88 to 90C. Radios close to your temps.

After 15 mins, here are the temps:
Cpu - 61C
5Ghz - 43C
2.4Ghz 39C

Since the 12V fan is running at 9V it is a bit slower and not very noisy.

In any case, thanks for the effort!

 

[JGrana]

Before stating "it's too hot", has any of you read the Broadcom specs determining how hot is too hot? How do you know that it's TOO hot? Right now, people are basing decisions on mere opinion, with no factual data. When I asked an engineer who actually works with various Broadcom SoC, he told me that some of these chips were rated for as high as 130C.

I used to have an ATI video card that would hit over 100C under load. The card never had any stability issue, the chip was designed to run that hot.

This is why I was hesitating about adding CPU temperature, and I am considering removing it. Brainslayer had the exact same train of thought with DD-WRT after he added the CPU temperature.

If people are going to get paranoid about temperatures, then I will simply remove them from the webui.

I work with a company that uses Broadcom parts (mostly 10G switches). We are evaluating a potential design that would use this part. From what a HW engineer told me, the 4708 has a Tj max (Thermal Junction) of 125C.

Is the DMU reading from the die? If so, there is lots of headroom...

Merlin - please don't remove the reading.

 

[RMerlin]

Is the DMU reading from the die? If so, there is lots of headroom...

I suspect so, since the DMU handling is in the Broadcom platform-specific bits of the Linux kernel. I found one reference here, in the dmu_temperature_status() function inside arch/arm/plat-brcm/bcm5301x_dmu.c.

We would need the reference documentation and someone with the knowledge to understand it to know for sure.

 

[TonyH]

Hi,
In my working on main frame days(say super computer), 90 deg. C was first stage temp. warning which triggers beeping alarm, then when it reaches 120 deg. C it is 2nd stage which shuts down the cabinet. One thing I do know from experience is when temp. gets hotter than usual, circuit becomes sluggish and noise level increases. Also I had an occasion to look under a microscope opened IC which suffered a partial damage from excess heat or static charge. subtrade junctions were partially burnt out or melted away which cause intermittent operation. The chip is still not dead but not 100%. When this kinda component is present it used to drive us nuts trying to trace what's going on. For an example, with this partial damaged component on board, heavy number crunching ops. will produce one glitch after 30, or 50 thousand loops. Also this things are designed/made under different specs. consumer grade-spec. mil-spec, commercial/industrial -spec. My experience is mostly under mil-spec. environment.

 

[greggy101]

If people are going to get paranoid about temperatures, then I will simply remove them from the webui.

Please do not.

 

[DaveMishSr]

Before stating "it's too hot", has any of you read the Broadcom specs determining how hot is too hot? How do you know that it's TOO hot? Right now, people are basing decisions on mere opinion, with no factual data. When I asked an engineer who actually works with various Broadcom SoC, he told me that some of these chips were rated for as high as 130C.

I used to have an ATI video card that would hit over 100C under load. The card never had any stability issue, the chip was designed to run that hot.

This is why I was hesitating about adding CPU temperature, and I am considering removing it. Brainslayer had the exact same train of thought with DD-WRT after he added the CPU temperature.

If people are going to get paranoid about temperatures, then I will simply remove them from the webui.

I would just go ahead and remove the cpu temperature Merlin. You must have posted this same info 2 or 3 times that I can remember and people still complain about it. Just take it out and save yourself the trouble of constantly having to respond to this.

 

[TonyH]

Hi,
Temperature monitoring does it's job. Matter is how a user reacts to the reading. Instead of worrying and complaining, s/he ought to do some thing about it.

 

[ronan_zj]

which firmware reads CPU temp? merlin build?

 

[greggy101]

which firmware reads CPU temp? merlin build?

yes, it does

 

[ronan_zj]

my room temperature is around 17-20 degree C, and AC68U is around 65-70 degree C, is this in normal range?

 

[greggy101]

my room temperature is around 17-20 degree C, and AC68U is around 65-70 degree C, is this in normal range?

It is perfect! or too low?
My CPU temp is around 90C and I care less. Room temp 24C

 

[netmik3]

Yeah i dont care about it being "hot" I was just trying to get it as cold as possible. It didn't drop so be it. I too have run graphics cards 24/7 at 96c with no issue except burning your hand.

Please don't remove CPU temp. I think what people mean by too hot is that asus could have tried to get it colder if possible, eg. use thermal grease, larger heatsink and who knows whats under the rf shield. It could be pretty easy to drop it by 10 degrees. Sure the chip can run hot but if it is that easy to drop it, why not. It might effect life over the long term.

IF they tried their best and its still 90c then its fine. But it seems asus didn't really care. Look at n66u pre production vs AC68u, they skimped on every single thing. I still miss the sd card reader. Why did they care so much for the n66u with GIANT heatsink and almost put a fan vs now with NOTHING.

I only stick with merlin so no r7000 for me. Plus this thing is pretty stable for me, I also lost half my resale value unless someone can source me a new sticker

One thing I dont like is the ddr utility. After release cpu turbo is pretty intuitive. But the proprietary ddr utility is bs. Does it really change nvram? Why cant the make it independent of the firmware and just flash the cfe permanently.

 

[ronan_zj]

Thats true because CPU or whatever chips do have temperature thresholds, so our stuff is safe as long as the temp is under the designed threshold. However, we always want to optimize our stuff to get the best performance. lol, AC68U has dual core, so we can add more functions in future into the router and the CPU won't be over loaded and pass the critical temperature.