This only makes sense if you have an iGPU, but hear me out.
My system:
CPU: Intel Core Ultra 7 265K
GPU: AMD Radeon RX 9070
Motherboard: MSI PRO B860-P WiFi
RAM: G.Skill 64GB (32GBx2) DDR5-6000
PSU: Corsair RM850X
OS: Arch Linux KDE
I see people always telling others to connect their monitor directly to the dGPU instead of the motherboard/iGPU. I decided to test this with a wattmeter, and the results were interesting.
Power consumption (whole system):
Connected to dGPU:
Idle at 60/165Hz: 33-35.5W (constantly fluctuating)
YouTube 1080p fullscreen: 73-83W (constantly fluctuating)
Connected to iGPU (motherboard):
Idle at 60Hz: 31.8W
Idle at 165Hz: 32.5W
YouTube 1080p fullscreen: 40-44W (occasionally hitting 50-52W)
Not only while playing youtube , doing any light tasks like opening new tabs, moving windows, browsing, chatgpt, claude etc all these things consume about 25-40W more when connected to dgpu directly. Also the system gets to idle power quickly when connected to igpu. Whereas with dgpu, it takes noticeably longer to drop to lower power levels.
When doing GPU intensive tasks like gaming or running LLMs, the OS (at least on Linux, should be the same on Windows) automatically runs them on the dGPU. I get the same performance, or at worst within margin of error.
So, it makes no sense to connect directly to the dGPU unless you’re only gaming. If you have mixed workloads - work, browsing, movies, youtube AND gaming , then connecting to the iGPU saves significant power without sacrificing performance where it matters.
I think this slightly increases latency for dGPU output though
Maybe on a desktop with unlimited tdp available the difference is negligible. Assuming your iGPU is strong enough.
But on my laptop using the built in screen I lose about 10-15 watts of CPU power which depending on the load, halves my frame rate. simply pushing those pixels to my display uses 30+% of the IGPUs ability.
And that’s assuming that the program you want will correctly run on the GPU you want. I spend more time messing with the configs than actually using some programs all because notepad needs an rtx 4090 or a game needs intel graphics. When it’s plugged into the dgpu it always uses the “correct” GPU.
You can also downgrade your PC and run a much less power intensive set up if you’re only doing a limited range of activities on it.
…you can even just write, or do maths on paper if you want, and keep those documents in folders. Still write “My Documents” on the folder of course.
I feel like you either missed this part or skipped it for some other reason.
When doing GPU intensive tasks like gaming or running LLMs, the OS (at least on Linux, should be the same on Windows) automatically runs them on the dGPU. I get the same performance, or at worst within margin of error.
…and set that folder down next to a running shopvac labeled “OneDrive”
I’ve had bad luck with Linux automatically using the dGPU even though I have to do this because I’m using a Tesla P4 which doesn’t have display output.
