Director, Marketing Communications
Director, Marketing Communications

The Problem with Running Naked for Crypto Currency

February 28, 2018 by Jason Lackey
The Tandy Radioshack TRS-80
The Tandy Radioshack TRS-80

One of the great things about technology is that each generation is presented with the opportunity to learn things anew. Remember the mainframe, particularly something set up for timesharing? Supposedly the PC killed them off, except that some would argue that they came back as The Cloud. Another example, the TRS-80. One of the first computers I used, the “Trash 80” is a dead machine that was sold by a dead company (Radio Shack) that shipped with a shiny Zilog Z-80 CPU running at 1.77 MHz. Packed with a massive 4K of RAM and a BASIC interpreter originally based on Palo Alto Tiny BASIC. The display was a snazzy black and white CRT. Later, an upgraded Level II BASIC, provided by a little known at the time company, Microsoft, was available for $120 including installation. Best of all, you could use unreliable and flakey cassette players for data storage.

Anyway, the whole reason for this trip down nostalgia road is to talk about RF emissions and interference – a couple things that the TRS-80 Model 1 came to be famous for. With a modular design such that each component and its cables could act like an (unintentional) RF transmitter, FCC Part 15 Subpart J, new regulations that cracked down on sources of RF interference spelled the end of the Model I. All in all, not a bad thing, as the Trash-80 and clones thereof were known for taking out nearby TVs and other devices. Indeed, emissions were so bad that an AM radio placed on top of the machine could be used for game sound effects. From there it is not a long leap to Van Eck phreaking, but we digress….

As PCs evolved and standardized, RF shielding improved. Even relatively thin metal inside plastic cases did a reasonable job, up to a point. Even fancy gaming rigs with windows in the case were not too bad, but a recent paradigm shift has created significant sources of EMI in some areas.

Enter the Mining Rig 

Unshielded mining rig
Unshielded mining rig illustrates the challenge nicely. Remember how we opened talking about The Cloud recapitulating the mainframe? Now we have crypto currency mining rigs recapitulating the TRS-80. Let me explain…

The TRS-80 had an emissions problem due in part to a modular design with lots of cabling that not only connected the modules but which could also act as antennas. Many cheap and dirty mining rigs share a similar architecture – no shielding, modular design with boards and components hung out in the open air for cooling.

In late 2017 a user on Reddit reported issues with an overclocked rig generating enough problems for 800mhz LTE that NKOM, the Norwegian version of the FCC, ended up tracking down a rig running GTX-1070 GPUs overclocked to 4400MHz and politely asked the owner to shut it down until he was able to properly shield the rig in question.

The Antminer S5
The Antminer S5

In November, 2017, FCC agents, in response to a complaint by T-Mobile about interference with their 700MHz LTE service, went looking for the source of the trouble. They found it in a Brooklyn apartment where an Antminer S5 mining rig (image courtesy of Bitcoin Forum) was found. Unsurprisingly, when the rig was powered down, the interference stopped.

However, challenges associated with unshielded Bitcoin rigs go back further. One 2014 example from has a user discussing his experience running an 11 card mining rig that evidently had created difficult to track down problems for Verizon. Eventually a couple techs tracked down the source and asked the owner to shut the rig down until he is able to get some shielding in place. Another example, also from, relates the experience of a gent in Eindhoven who attracted unwanted government attention via an unshielded rig creating problems for a nearby radio listener.

Which brings us full circle, back to the old TRS-80, where interference so horrible it was audible on the radio was used as a feature.

Anyway, for those running naked mining rigs, one thing you can do to be a better neighbor to those also using the electromagnetic spectrum is to deploy some shielding. In many cases aluminum foil will do the trick, two layers if you want to be sure. Just be careful you don’t short out your boards by having the aluminum foil touch – it may make sense to foil a cardboard box that fits over the right, perhaps with some small holes to vent hot air.

And of course, if you are using aluminum foil for RF shielding, be sure to save some for your tinfoil hat.

Thanks for reading.