MBP 2012-2015 Loud Fans with 4K

Hardware
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I’ve been running a 2012 Retina MBP 2.6/16/256 (now an Aura 1TB) since they were released (the first Mac I actually longed for enough to pre-order, and my first was a IIx) and it has been the workhorse of my dreams, mostly doing visual design and web dev work with occasional Logic and video editing use. I had to replace the trackpad under AppleCare, and I paid for a fresh battery less than a year ago, but otherwise problem-free.

I decided to pick up a 4K monitor (Samsung U28E510) once they came down in price this year, only to find my fans blowing 5-6000 RPM regularly. Sometimes with just a couple of web apps open.

I chalked it up to my MBP being a 2012 model with Thunderbolt 1 and a 1GB Nvidia 650M which arguably should (and does in fact) drive a 4K monitor with SwitchResX, though not at 60fps and not officially supported on TB1 without MST.

I am currently of limited means, so I put up with the aircraft hangar fan noise for a good six months, then decided to take an educated gamble and crossgrade to a used final pre-touchbar retina, the 2015 BTO 2.8/16 with a 2GB Radeon R9 M370X. Found one on eBay in great shape for $1600, and figured I could roll my 2012 for $800-$1200 depending on which SSD I include (512 or 1TB).

I resisted buying a 2016 touch-bar Mac for a number of reasons, including the USB-C dongle situation (all my current HW is quite comfortably TB2 or USB3, particularly my OWC TB2 dock, several UA Apollos with a tethered FW UAD Satellite), the exorbitant cost of a non-replaceable 1TB SSD, the butterfly keyboard, and the, uh, touchbar itself.

I was hoping that the bump in GPU and the TB2 MST would calm the fan situation so I could edit audio in relative peace without breaking the bank. The bump in CPU and the SSD 4X lanes (easily 4X faster than the 2012 in actual use) seemed like a bonus.

It’s been three days, and so far, I was VERY WRONG.

The 4K monitor now works great with 60fps at the highest resolutions, but I am disappointed to find the fans are pretty much the same, blowing 6000 RPM running just Photoshop, Illustrator, Sketch, or a robust web app like Figma or InVision.

Is constant fan noise the new normal for MBPs running 4K displays?

FYI I was running Sierra on the 2012 which had probably migrated up from 10.8 or 10.9 one OS at a time, I very purposefully started with a clean High Sierra install on this machine, only replacing/installing things as I find myself requiring them – which is pretty aggravating time and effort-wise, but means I am currently using a lean 250GB vs. 750GB on my old SSD, which will go in an Envoy when I sell the 2012.

I admittedly haven’t blown out the innards of the new Mac, so there’s that.

Any insight into my situation?

Those of you with Touchbar MBPs, how is the fan situation when you plug into 4K displays?

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Are you sure the problem isn’t the monitor? Can you switch it out with another monitor as a test (4K or not) and see what happens? I have a 2016 MBP with Touchbar that is as quiet as a mouse with a Dell HD monitor (not 4K though). I just updated Mojave yesterday.

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Hmm… interesting thought. I drove a 1920x1080 monitor from it for nearly two years and it didn’t impact the fan speeds perceptibly, so I assumed it was the leap to 4K that was the issue.

Can different UHD displays of the same resolution affect Macs differently? Hadn’t really occurred to me. Although now I’ve driven the same display with both Nvidia and AMD graphics cards with similar temperature impacts to both.

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If you do the very same work on the built in display, do the fans speed up?
I don’t think it’s the monitor, I think it’s what the monitor allows you to do.
My 2015 rMBP runs quietly driving a 4K monitor until I start getting work done, then the fans speed up or slow down, depending on CPU load.
iStat Menu or Activity Monitor might giv you more insight into cpu load, etc.

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I have a 2016 MBP (the first year) with the 5K display and no fan noise for normal work. Only when using some app that cranks the CPU up does the fan start up (and then frankly it’s fairly quiet in my view).

I do notice that the fan will pick up if I’m watching 4K content on YouTube for example. I think this is primarily because this MacBook doesn’t have the hardware decoding for 4K like it does for 1080p content. Watching a 4K stream on YouTube will crank my CPU to a constant 20% which is enough to heat up the CPU enough to bring the fans up to about 5k.

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