For year , referee have intermittently reported see to it static on external show after waking them from sleep , but we had a new one arrive recently : a couple had the job occur on each of their displays . There ’s no pattern they see , and , as with previous correspondents , turn the display off and on pass the result .
While there ’s no one answer , enquiry pass water it appear as if either the cableora protocol carried over the cable is the issue . you may trouble-shoot this fairly easy bet on the model of Mac and presentation you have .
The HDCP ( High - Bandwidth Digital Content Protection ) communications protocol runs behind the shot on all devices that conform to HDMI or DisplayPort specifications ( include using them over Thunderbolt or USB ) as a comic effort to prevent piracy . HDCP demand a form of “ handshake ” between the host gadget ( a Mac or other figurer ) and a display . If the handclasp give out , which can bechance if there ’s a slight delay after the Mac wakes and the display does n’t get the response it needs , you might see static . Unplugging the cable , power cycle the display , or press Esc at a login window CRT screen and then press any key should empty the state , but only once .
Some masses have found that change out their cable solves the problem , whether the source is HDCP or a cable issue . HDMI cables are fink for especial performance . You do n’t need a specially gold - plated one that costs 20 times as much as a normal cable , but you almost for certain need an HDMI High Speed cable or good , which begin at under $ 10 .
All DisplayPort overseas telegram can handle any declaration and refresh , but because Apple only uses USB - nose candy and HDMI porthole for carry video information , you are likely using either an HDMI - to - HDMI cable , a USB - carbon - to - HDMI cable television , or a USB - vitamin C transcriber or dock with an HDMI port in it . If your video display has native USB - blow support and you have a supererogatory port , try a USB - C - to - USB - C line .
This Mac 911 clause is in response to a question submitted by Macworld reader Jim .
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