Technology

37738 readers

50 users here now

A nice place to discuss rumors, happenings, innovations, and challenges in the technology sphere. We also welcome discussions on the intersections of technology and society. If it’s technological news or discussion of technology, it probably belongs here.

Remember the overriding ethos on Beehaw: Be(e) Nice. Each user you encounter here is a person, and should be treated with kindness (even if they’re wrong, or use a Linux distro you don’t like). Personal attacks will not be tolerated.

Subcommunities on Beehaw:

This community's icon was made by Aaron Schneider, under the CC-BY-NC-SA 4.0 license.

founded 2 years ago

MODERATORS

TheRtRevKaiser@kbin.social

115

WTF? This computer's CPU fan is powered on by only a HDMI monitor (streamable.com)

submitted 1 year ago by JustARegularNerd@aussie.zone to c/technology

26 comments fedilink hide all child comments

I actually intended to post this to Reddit but I thought I would contribute content to here instead to get the ball rolling here and do my part.

Anyway, this is a Windows XP-era machine I have at work for testing, and I had just this monitor plugged into it and saw the CPU fan trying to spin. I spun it a bit myself and it just kept going. I disconnected the HDMI cable and it stopped.

The monitor is actually DisplayPort, with a passive adapter to HDMI which then goes to the HDMI cable connected to this PC. The GPU is just PCI-E. The computer has some old ~2007 AMD CPU in it. The GPU actually doesn't seem to work anyway, the PC posts normally but there's no image from either the GPU or onboard, but when putting either another GPU or no GPU, there's an image from the appropriate output.

you are viewing a single comment's thread
view the rest of the comments

[–] themoonisacheese@sh.itjust.works 25 points 1 year ago (1 children)

HDMI has a 5V power rail (your adapter isn't passive, it's just parasitic on that rail). I'm guessing that this old hardware isn't equipped with diodes everywhere, and the fan 5V is connected directly to the PCIe 5V rail, and the card is also not shielded and so the 5V rail ends up directly connected to the monitor.

If i was to guess I'd say that the adapter itself also has a part in this. I think it is sending back power when it shouldn't.

[–] JustARegularNerd@aussie.zone 1 points 1 year ago

Yeah, I think this is the most logical explanation.