#5,425 in Computer accessories & peripherals
Reddit mentions of Accell mDP to HDMI Adapter - Mini DisplayPort 1.2 to HDMI 1.4 Active Adapter - 4K UHD @30Hz, 1920X1080@120Hz, 2560X1600@60Hz - Polybag, Model:B086B-007B-2
Sentiment score: 1
Reddit mentions: 2
We found 2 Reddit mentions of Accell mDP to HDMI Adapter - Mini DisplayPort 1.2 to HDMI 1.4 Active Adapter - 4K UHD @30Hz, 1920X1080@120Hz, 2560X1600@60Hz - Polybag, Model:B086B-007B-2. Here are the top ones.
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- Connect your PC or Mac with mini DisplayPort to any HDMI display
- Supports resolutions up to 4K Ultra HD @30Hz, Full HD 1080p @120Hz, and WQXGA @60Hz (2560x1600)
- Compliant with DisplayPort 1. 2, HDMI 1. 4b, DPCP, and HDCP 1. 3
- Active adapter technology is universally compatible with all Mini DisplayPort
- No driver software or external power supply required
Features:
Specs:
| Height | 0.5905511805 Inches |
| Length | 8.0708661335 Inches |
| Number of items | 1 |
| Release date | August 2018 |
| Size | Mini DisplayPort 1.2 to HDMI 1.4 |
| Weight | 0.0001984160358 Pounds |
| Width | 2.755905509 Inches |
I had the same issue initially, and also helped a co-worker sort out the same problems. Are you using an adapter of any sort? If so, it needs to be an 'active' HDMI 1.4b adapter like this one. I'm using that exact adapter to connect my Lenovo W540 to the 39" Seiki and I have zero issues.
You also need to make sure that your graphics card can handle HDMI 1.4b. A $60 R7 250 can, so I assume that most newer cards can, but some older cards may not support the newer HDMI spec.
Any Mini-DP adapter that's fully compliant with HDMI 1.4b should work fine. Your adapter may not be 1.4b compliant, and if it's not it would be limited to 1080P @ 60Hz as you described.
We're talking about the same Macbook Air, right? [This one] (http://support.apple.com/kb/sp678)? If so, I've seen that people have had success with [this] (http://www.amazon.com/dp/B00F90H77A/ref=cm_sw_su_dp) active Mini-DP to HDMI adapter and the Seiki SE39UY04 (It's compliant with up to HDMI 1.4b, which is the standard that enables the seiki's 3840x2160@30Hz resolution). While the specs for the computer state 2560x1600 as a max resolution, they're assuming 60Hz. The Seiki is running at 30Hz, therefore requires a Pixel Clock that's around the same speed as running 2560x1600@60hz or 1920x1080@120Hz (the seiki has a pixel clock of 279Mhz to reach 4K@30Hz, HDMI1.4b spec maxes out at a pixel clock of 300Mhz, which that adapter supports), all of which falls under the HDMI 1.4b standard -- As a bonus you can add 1920x1080 @ 120Hz or 1280x720 @ 240Hz as custom resolutions with SwitchResX.