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I wonder: isn’t this just the kind of things electronics get FCC tested for? How did nvidia get accredited by an FCC certified lab given the strong emissions in

by fra 8y ago

I wonder: isn’t this just the kind of things electronics get FCC tested for? How did nvidia get accredited by an FCC certified lab given the strong emissions in those bands?

Scoundreller 8y ago
My guess: it ain't certified to be run in open-air, only inside a grounded and enclosed case/tower.
tjohns 8y ago
Your computer's metal (theoretically enclosed, hopefully grounded) case provides essential RF shielding. If you run in an open-air configuration, you're going to get RF noise. One of my roommates has a computer case with an acrylic window — typical DIY gaming PC case. That window means the case provides poor shielding. When the computer's on, it sputters all over the 70cm ham band.
blattimwind 8y ago
Graphics cards only have to comply to EMI standards while mounted inside a computer chassis. Ultimately the person/company putting a computer together (or importing it) is responsible for the whole computer adhering to EMI standards.
- exikyut 8y ago
  Heh, I just pictured a GPU inside an empty PC case, and then immediately realized of course that wouldn't work, and am now wondering, how do you generate the necessary load to correctly EMI-test a GPU? Do GPUs include a secret "crank everything to 11" test mode feature that exercises all the cores and RAM and everything, so you can just bolt it into a case, maybe connect it to a fake motherboard that supplies 3.3V or whatever so the card initializes properly... or do vendors test with a massive pile of motherboards, measuring and offsetting for the EMI generated by each motherboard?
  - SAI_Peregrinus 8y ago
    If the GPU + Motherboard passes EMI compliance, then the GPU - Motherboard must also pass, since the motherboard doesn't provide shielding but only adds noise. So I don't think the particular motherboard should matter. The measured interference will always be >= to the real interference produced by the GPU under test.
    - exikyut 8y ago
      Hmm, good point, didn't quite look at it that way. But now I'm wondering if there are motherboards out there that radiate a little bit more than they should, and force peripheral vendors to do extra work clipping EMI in their own products. This is probably not true, since all PCI card vendors would have to test their products with tons of different boards.
makomk 8y ago
It's probably partially that devices are tested individually, and a large collection of compliant devices can put out quite a bit of total RF. This isn't just a cryptocurrency mining problem; even before that was invented, the total RF emissions of our modern technological society had already pushed up the RF noise floor substantially. HF ham radio is often near-unusable in urban areas and licensed UHF/VHF business radio users have had to push up their power compared to what was previously allowed in order to get the range they need.

by fra 8y ago

I wonder: isn’t this just the kind of things electronics get FCC tested for? How did nvidia get accredited by an FCC certified lab given the strong emissions in those bands?

Scoundreller 8y ago

My guess: it ain't certified to be run in open-air, only inside a grounded and enclosed case/tower.

tjohns 8y ago

Your computer's metal (theoretically enclosed, hopefully grounded) case provides essential RF shielding. If you run in an open-air configuration, you're going to get RF noise. One of my roommates has a computer case with an acrylic window — typical DIY gaming PC case. That window means the case provides poor shielding. When the computer's on, it sputters all over the 70cm ham band.

blattimwind 8y ago

Graphics cards only have to comply to EMI standards while mounted inside a computer chassis. Ultimately the person/company putting a computer together (or importing it) is responsible for the whole computer adhering to EMI standards.

exikyut 8y ago
Heh, I just pictured a GPU inside an empty PC case, and then immediately realized of course that wouldn't work, and am now wondering, how do you generate the necessary load to correctly EMI-test a GPU? Do GPUs include a secret "crank everything to 11" test mode feature that exercises all the cores and RAM and everything, so you can just bolt it into a case, maybe connect it to a fake motherboard that supplies 3.3V or whatever so the card initializes properly... or do vendors test with a massive pile of motherboards, measuring and offsetting for the EMI generated by each motherboard?
- SAI_Peregrinus 8y ago
  If the GPU + Motherboard passes EMI compliance, then the GPU - Motherboard must also pass, since the motherboard doesn't provide shielding but only adds noise. So I don't think the particular motherboard should matter. The measured interference will always be >= to the real interference produced by the GPU under test.
  - exikyut 8y ago
    Hmm, good point, didn't quite look at it that way. But now I'm wondering if there are motherboards out there that radiate a little bit more than they should, and force peripheral vendors to do extra work clipping EMI in their own products. This is probably not true, since all PCI card vendors would have to test their products with tons of different boards.

makomk 8y ago

It's probably partially that devices are tested individually, and a large collection of compliant devices can put out quite a bit of total RF. This isn't just a cryptocurrency mining problem; even before that was invented, the total RF emissions of our modern technological society had already pushed up the RF noise floor substantially. HF ham radio is often near-unusable in urban areas and licensed UHF/VHF business radio users have had to push up their power compared to what was previously allowed in order to get the range they need.