Which computer power supply produces little or no dirty electricity?

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So far I've only found certain laptops produce a comfortable amount of EMI for me, which is 100mV or less. My laptops all run on 65W adapters and can idle around 10W. Older laptops with dual-core Intel "U" chips are tolerable for me, but quad-cores are not comfortable for me even if EMI is low. With some computers I've found that EMI produced scales with the wattage the machine is using at a given time, so EMI increases as CPU load increases. An Acer gaming laptop I tried produced 400-600mV EMI while idling at 15W, but quickly jumped to +1000mV once pulling 40W. On the two desktops I've tried recently that wasn't the case; EMI was high (+1000mV) whether at idle or under load and they're very draining to use them because of that. My Dell Latitudes measure around 100mV at idle or full load, which is ideal for me.

Laptops can use smaller power supplies, and the lower TDP chips means less watts needed. Less watts means less AC/DC conversion, which should produce less EMI, but maybe this isn't always true. This works for my ES, but it puts a cap on how much computing power I have access to.

Did you know in Windows that you can throttle the CPU?  I was once given a work computer that was giving me problems, so I throttled both CPUs to 50%, and that was better for me.  Of course, that meant that some things were running twice as slow, but so be it.

I think the next computer they'll be giving me at work may have 8 cores.  That'll be interesting.

Marc
 

Here is an article on Power Throttling.  It may not work on older computers (doesn't on my old ThinkPad 140.)

 https://blogs.windows.com/windows-insider/2017/04/18/introducing-power-throttling/#:~:text=With%20%E2%80%9CPower%20Throttling%E2%80%9D%20%2C%20when,is%20spent%20on%20that%20work.

Marc, I sent you a message via forum email, please check your spam folder if you didn't see it in your inbox. The regular price of the supplement I mentioned is $49.95, this week only it's 30-40% off I think, must call to get the Special price.

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Yeah, when I've custom-configured my Lenovo Tower PCs, I've always gone for the less-efficient power supply option.  As energy efficiency generally cause me issues.

But I've just ordered an energy-efficient ethernet switch, so I'll be testing out that theory yet again, soon.

Marc
 

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I just tried a Corsair RM850x because it's the best in category for EMI's on Tom's Hardware. on the Line EMI meter though, it's around 1000mV.. so it's not low at all.. with a video card, you'd get 1500mV.
Corsair HX1000i same thing,..
I have another 2 year old supply either 450 or 550 I will have to check details, that emits no noticeable difference on the Line EMI!.. Antec or Thermaltake, I'll check tomorrow. It seems the lower the wattage the less line EMI. Another Fractal 660P (Too smelly/horrible) does quite a bit better than the RM850x.

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When custom ordering Lenovo towers, I've always gone for the low-efficiency power supply option.

So what exactly are you using for an in-line EMI filter?

Thanks,
Marc
 

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On April  5, black-sun [via ES] <[hidden email]> wrote:
> I bought this in-line EMI filter.

Ah, so you are saying that the quality of the power coming in from the AC line is impacting the quality of the power coming from the PC internal power supply.  I often wonder how independent/dependent these two things are.

BTW, I just got a new desktop tower PC from my employer while working at home.   Really awful.  A Dell Precision 3630.  Avoid at all costs.   So far I have found it helpful to move it away from me (longer cables, making it 9 feet away instead of the usual 3 feet), draping it in a grounding sheet (the kind you're supposed to use on a mattress), and surrounding it with RF absorption material.  I also found that putting sheet metal nearby made things worse, presumably it's reflecting some of that noise back towards me.

I still have some other things to try, but so far my groundrules are to NOT open it up and mess with things inside of it.

Marc