ajay

I did something similar. I recorded 4k 24p HQ externally via the Atomos with no cards in for 35 mins or so. Then shut the camera and inserted the CfExpress card and tried to record in 4k120fps and see how much time I get. I only got 5 mins left in 4k 120!! So this tells me, using the ninja V is only good for recording 4k HQ 24 fps and after that the camera becomes useless for any high frame rate recording in 4k, let alone 8k. Got hit hard with the cripple hammer lol. 
 
 

I suspected Canon to cripple this camera somehow, someway but this artificial heat limit and recovery time is really out of line. Such arrogance!
But you know what? Canon may think they control the market but we have the power to control them by boycotting Canon. Especially nowadays with the camera industry bleeding as it is. Force Canon to stop this BS. How?
If you already purchased the camera, return it. If you have it on order, cancel it. Cancel all orders with Canon. Write letters to Canon showing your disgust. Call Canon and voice your disapproval. Fight Canon with your pocketbook. Stop the BS.

How about opening the back of the unit w/o disconnecting anything. Blow air across the inside of the camera using a small muffin fan and record as you normally would. The temperature should definitely stay cooler. Check run times and recovery times.
If it's crippled by firmware, times shouldn't change. If recovery times are drastically reduced, it is strictly their way of managing the temperature of the camera.
My guess is, it's probably both. But it would be interesting to see how a fan blowing directly on the components changes things.

Very interesting stuff! I'm a hobbyist Canon shooter myself, but I'm still on the EOS 6D since until now I couldn't find anything that really pushes me towards a new camera. The R5/R6 might be the one that actually catch me. However, after reading all of this, I get doubtful.
Besides that I'm an engineer for embedded software / electronics (in automotive) and I would like to share some of my knowledge here.
1. As horshack already pointed out the temperature written in the EXIF might not be the temperature of the main controller, but the one of another chip that's supposed to be a "good"/"reasonable" representation for the inner camera temperature.
2. From our electronics I know that we usually measure 4-5 temperatures from different chips and the differences are quite astonishing sometimes. While the main chip under "heavy duty" might be at around 90°C within a few minutes, peripheral chips show the temperature increase with a (for me) surprisingly high delay of a few minutes. This is partly due to the fact that thermal operations take quite some time, especially if the heat distribution medium is air. This depends on the placing of the chips of course.
3. The issue might not be overheating of the main controller, but of another chip, e.g. of the sensor read out circuit
4. There has been some discussion about maximum temperatures of electronic chips. It is correct that 90°C is still in the comfort zone of most electronic chips. However, you have to take into account that there is a maximum allowed temperature for surfaces is 65°C (Metal) and 85°C (Plastic) due to safety reasons (Source, as an alternative google "safety standard maximum heat surface", Alternative Source). The second source even limits to 55°C for prolonged usage and 60°C for "Short periods only".
I saw some videos in which they managed to shoot 4k HQ continuously for hours, by removing the cards from the camera. If I combine the "safety" stuff with this I get to the conclusion that the issue might be the memory card getting too hot in terms of safety regulations. Here's my scenario: I record for let's say 45 minutes, before my CFexpress card is full. I want to switch cards quickly -> I directly open the card slot and pull out a card that has a temperature of ~80-90°C. This is not acceptable by means of safety.
The only thing that bothers me then is that the temperature should go down much much faster than what's seen here. Especially, if you look at the "tests" that Jordan from dpreview did, in which he removed cards and battery completely. After that the temperature should go down much faster. Something I can imagine here is that they cannot directly measure the temperature of the memory cards. Due to this they use a formula for calculating cool down times. This formula does not take opening the card slot or changing the card into account.
I hope Canon will release detailed information about this. Because even though I'm a stills shooter only, I don't want to be tricked. And I must admit I'm on the edge to switching to Sony, anyway.

I suspected Canon to cripple this camera somehow, someway but this artificial heat limit and recovery time is really out of line. Such arrogance!
But you know what? Canon may think they control the market but we have the power to control them by boycotting Canon. Especially nowadays with the camera industry bleeding as it is. Force Canon to stop this BS. How?
If you already purchased the camera, return it. If you have it on order, cancel it. Cancel all orders with Canon. Write letters to Canon showing your disgust. Call Canon and voice your disapproval. Fight Canon with your pocketbook. Stop the BS.

I suspected Canon to cripple this camera somehow, someway but this artificial heat limit and recovery time is really out of line. Such arrogance!
But you know what? Canon may think they control the market but we have the power to control them by boycotting Canon. Especially nowadays with the camera industry bleeding as it is. Force Canon to stop this BS. How?
If you already purchased the camera, return it. If you have it on order, cancel it. Cancel all orders with Canon. Write letters to Canon showing your disgust. Call Canon and voice your disapproval. Fight Canon with your pocketbook. Stop the BS.

I suspected Canon to cripple this camera somehow, someway but this artificial heat limit and recovery time is really out of line. Such arrogance!
But you know what? Canon may think they control the market but we have the power to control them by boycotting Canon. Especially nowadays with the camera industry bleeding as it is. Force Canon to stop this BS. How?
If you already purchased the camera, return it. If you have it on order, cancel it. Cancel all orders with Canon. Write letters to Canon showing your disgust. Call Canon and voice your disapproval. Fight Canon with your pocketbook. Stop the BS.

I suspected Canon to cripple this camera somehow, someway but this artificial heat limit and recovery time is really out of line. Such arrogance!
But you know what? Canon may think they control the market but we have the power to control them by boycotting Canon. Especially nowadays with the camera industry bleeding as it is. Force Canon to stop this BS. How?
If you already purchased the camera, return it. If you have it on order, cancel it. Cancel all orders with Canon. Write letters to Canon showing your disgust. Call Canon and voice your disapproval. Fight Canon with your pocketbook. Stop the BS.

I suspected Canon to cripple this camera somehow, someway but this artificial heat limit and recovery time is really out of line. Such arrogance!
But you know what? Canon may think they control the market but we have the power to control them by boycotting Canon. Especially nowadays with the camera industry bleeding as it is. Force Canon to stop this BS. How?
If you already purchased the camera, return it. If you have it on order, cancel it. Cancel all orders with Canon. Write letters to Canon showing your disgust. Call Canon and voice your disapproval. Fight Canon with your pocketbook. Stop the BS.

I suspected Canon to cripple this camera somehow, someway but this artificial heat limit and recovery time is really out of line. Such arrogance!
But you know what? Canon may think they control the market but we have the power to control them by boycotting Canon. Especially nowadays with the camera industry bleeding as it is. Force Canon to stop this BS. How?
If you already purchased the camera, return it. If you have it on order, cancel it. Cancel all orders with Canon. Write letters to Canon showing your disgust. Call Canon and voice your disapproval. Fight Canon with your pocketbook. Stop the BS.

This camera is an expensive EOS R mk2. Almost always you will be forced to record in the lineskipped 4K modes after one hour, no matter where you are shooting from arctic tundra to jungle. If you are ok with only having lineskipped 4K at 30p max then the camera is a OK upgrade from the EOS R.
Matt Johnson from WhoIsMatt tried to use it to film a wedding. His conclusion: be absolutely prepared to be shooting 4K 30p lined skipped 4K. And if you are a real video professional, then don’t get the R5. Spend your money more wisely.
Which is a real shame because a lot of other specs on this camera are very very nice. The AF is top notch, human and animal eye detection, size, weight, glass...it’s just a shame the 4K HQ isn’t the default recording mode because if it was this camera would be pretty damn amazing. I would recommend watching it. It’s one of the less bullshit filled videos out there on REAL WORLD use of the camera.
 

I differ in opinion.
If I where using it as designed, yes. The fact of the matter is that canon disclosed up front that there are recording limits. They can not anticipate every single usage scenario, so provided generic guidelines.. it’s not realistic to expect them to know how every single user is going to use their camera.
I’ll answer with a question: do you find yourself implicitly trusting every advertisement you see? I don’t and I seriously doubt that you do.

You are wrong.
I cannot legally advertise a product I've made as a professional cinematography camera, when it is in fact a banana.
I cannot please my customers or make good business selling something as "8K capable" when it isn't.
To say every company does it is just not true. In fact if they tried it, they'd be on wrong side of the law and wrong side of their customers.
Can you imagine the fury if your iPhone started overheating 1 hour into the day and you had to turn it off for 30 mins?
I am very baffled as to why you think Canon can get away something similar... because it's a camera.
No, they advertised it a certain way, and even the late admission of heat limited recording times is misleading because of how the camera behaves 10-20 mins after being switched on, or 30 mins into a stills shoot.

This is the nonsense I see on DpReview.  Apparently the camera is excused for not working reliably as its not a Professional video camera.  So why does it have 8K RAW, or 120fps 4K then?  Why provide such top video features only to cripple them?  And why is it so wrong to wish that they work as the customer requires, especially if you're paying over £4k for it.  I have video and photo functions on my phone.  Its neither a dedicated video or photo camera, yet I still expect these functions to work reliably.  Basic stuff.  How well would a phone do, if it advertised a limit on say web browsing.  You get 15 mins then it overheats and you'll have to switch off for a few hours before you can browse again.  It would be laughed at.
Canons description of the overheating limits is half a story.  There are some crucial inconsistencies their figures don't address.  Canon offered us a hybrid camera and advertised it as such.  The S1H is also a hybrid and not a true cinema camera; yet is far more reliable shooting HQ video.  Compare the R5 to that and not cinema cameras and you'll see what some of us were actually hoping for.

Who cares about a workaround for 4K24p?? Every camera does that since a long time. There is no workaround for 4K60p and 120p, recording externally is not option otherwise we would use proper cine camera if weight and size wasn't an issue. 
I am fine working with time limitations to get those heat producing features (like 15min max in 4K120) as long as taking stills / be in the menus do not lower those limitations and as long as the camera recovers similarly to any other camera on the market, and not in 2+ hours like it seems to be the case. 
For me it has never been about the initial time recording limitation, which are understandable, but about the recovery time and the camera heating by itself when on. The latter is what makes the camera barely usable for any usage and could have EASILY been avoided by Canon technically as proven by competitors. It's likely that they did make it more thermally efficient by purpose / and or put software limitation. If they actually did their best, which I do not believe a second, then they should fire the whole company (with managers first) and start from 0 or stick with making printers. What a joke. 
I went from "amazing, finally" when announced to "still great" when we heard about recording limitations to "WTF is this BS" when we found out that the camera is actually almost unusable for video due to the above. 
On top of that, my camera ordered day 1 still did not ship with no date in sight. That's actually probably a good thing since if Canon doesn't fix this I am afraid my testing period will very likely end up with a return. 

All these so called 'workarounds' really are an olympic sized exercise in turd polishing.

Maybe it was intentional? Cannons do get hot.

Have you heard of the pandemic?

These workarounds don't work for all modes. What about 4k 120p? Can't do that currently with an external recorder and even if you could, you've now lost compactness which makes it difficult or impossible to use in the field for wildlife videography.  It defeats the purpose of the camera for how I would use it.
Even if you primarily shoot stills, the damn camera heats up and makes it nearly unusable when you do want to take video.
I fail to understand why anyone would use these workarounds for a camera with bad engineering design. Why promote this garbage? Why spend thousands of dollars on a camera that works half-assed at best and requires you to spend another thousand to use it for some of it's video modes but not all?
If you want to stop Canon from making shit cameras stop buying them.
 

These workarounds don't work for all modes. What about 4k 120p? Can't do that currently with an external recorder and even if you could, you've now lost compactness which makes it difficult or impossible to use in the field for wildlife videography.  It defeats the purpose of the camera for how I would use it.
Even if you primarily shoot stills, the damn camera heats up and makes it nearly unusable when you do want to take video.
I fail to understand why anyone would use these workarounds for a camera with bad engineering design. Why promote this garbage? Why spend thousands of dollars on a camera that works half-assed at best and requires you to spend another thousand to use it for some of it's video modes but not all?
If you want to stop Canon from making shit cameras stop buying them.
 

Just for fun, I took the side-by-side video clip from both cameras and did a little tweaking to get them a bit closer to each other. (See below)
There's some truth to Canon's ability to produce a more pleasing look right out of camera but both cameras can certainly be adjusted to match. I have used Andrew's Pro Color adjustments in the A7III to produce "Canon Color" directly out of the camera by tweaking settings in-camera. That is one feature of Sony cameras that are often overlooked. You can tweak profiles to the nth degree. In current Sony mirrorless cameras however you can only do so much tweaking due to dynamic range limitations and 8-bit codecs.
Where the differences typically exist between these consumer cameras and production cinema cameras boils down to dynamic range and how many stops of light you have available in the highlights and shadows.
I am quite confident that the new A7SIII can be tweaked in-camera to produce many different "looks" straight out of camera and with better dynamic range and a 10-bit codec.

I can't remember what reviewer mentioned that they were amazed that after the camera cooled down to the point that the body didn't feel hot any more that their record times were still severely hampered. It does make you wonder if Canon's firmware is designed to purposely cripple this camera. I usually don't buy into conspiracy theories but one does have to wonder with Canon's history of intentionally crippling cameras.
 

Both Undone and Bloom are the best IMO. I always look forward to their reviews. I did learn a few new tidbits from Bloom's review of the A7SIII that are important to my style of work (wildlife):
Animal eye detect autofocus does not work in video (stills only). Philip has started a petition on this, here's the link if you want to sign this. Tracking autofocus does not work while using Clear Image Zoom. Tracking autofocus does not work while using an external monitor. Punch-in does not work (manual focus) while recording. Clear image zoom works to 1.5x. Lot's of positives with the A7SIII but there are negatives too. I wish this camera had Canon's autofocus capabilities. With that stated, I'd much rather deal with these issues than a camera that can't recover from overheating until hours later, has line skipping in 120p 4k and humongous file sizes.

Both Undone and Bloom are the best IMO. I always look forward to their reviews. I did learn a few new tidbits from Bloom's review of the A7SIII that are important to my style of work (wildlife):
Animal eye detect autofocus does not work in video (stills only). Philip has started a petition on this, here's the link if you want to sign this. Tracking autofocus does not work while using Clear Image Zoom. Tracking autofocus does not work while using an external monitor. Punch-in does not work (manual focus) while recording. Clear image zoom works to 1.5x. Lot's of positives with the A7SIII but there are negatives too. I wish this camera had Canon's autofocus capabilities. With that stated, I'd much rather deal with these issues than a camera that can't recover from overheating until hours later, has line skipping in 120p 4k and humongous file sizes.

Both Undone and Bloom are the best IMO. I always look forward to their reviews. I did learn a few new tidbits from Bloom's review of the A7SIII that are important to my style of work (wildlife):
Animal eye detect autofocus does not work in video (stills only). Philip has started a petition on this, here's the link if you want to sign this. Tracking autofocus does not work while using Clear Image Zoom. Tracking autofocus does not work while using an external monitor. Punch-in does not work (manual focus) while recording. Clear image zoom works to 1.5x. Lot's of positives with the A7SIII but there are negatives too. I wish this camera had Canon's autofocus capabilities. With that stated, I'd much rather deal with these issues than a camera that can't recover from overheating until hours later, has line skipping in 120p 4k and humongous file sizes.