Can't get full resolution with MacBook Pro 15" mid 2010 on a BenQ PD2500Q display

kjl3000 wrote:

I recently bought a BenQ PD2500Q Display with a native Resolution of 2560 x 1440 px. I'm trying to hook up my old MacBook Pro 15" mid 2010. As I'm also using this MacBook with the Apple 27" LED Display (pre-thunderbolt) via displayport I can't see why the BenQ Display isn't showing me the same 2560 x 1440 px in Monitor settings but is maxed out at 1080p. I tried connecting it with a mini Displayport to Displayport Cable, that is said to be displayport 1.2 compatible and therefore support up to 4K (see link for details: https://www.amazon.de/gp/product/B01LXW0GQI/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1) 

I also tried connecting it with an active minidisplayport to HDMI Adapter (https://www.amazon.de/gp/product/B071X692K7/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1), since the BenQ Display has mini DisplayPort, Display Port and HDMI Inputs, but also with no luck and a max of 1080p. I succesfully got full resolution with a 2017 MacBook Pro via Displayport and HDMI, but I need to get my old MacBook Pro to work on that Display.

I am really stuck here since I have no idea why my Apple 27" Display is working at full 2560 x 1440 px resolution via DisplayPort and the BenQ Display doesn't. I also contacted BenQ support but they say that since the Display works fine with a newer MacBook the cause should be between the Mac and the adapter and I should contact Apple. Since support has expired a long, long time ago, i don't expect Apple will help me on this one.

So any ideas and help would be highly appreciated.

THX

MacBook Pro (15-inch, Mid 2010) - Technical Specifications

https://support.apple.com/kb/SP582?locale=en_US

Graphics and video support

• NVIDIA GeForce GT 330M graphics processor with 256MB of GDDR3
• memory on 2.4GHz and 2.53GHz configurations; or 512MB of GDDR3 memory on
• 2.66GHz configuration
• Intel HD Graphics with 256MB of DDR3 SDRAM shared with main memory5
• Automatic graphics switching
• Dual display and video mirroring: Simultaneously supports full
• native resolution on the built-in display and up to 2560 by 1600 pixels
• on an external display, both at millions of colors
• iSight camera
• Mini DisplayPort

Pure digital video output

DVI output using Mini DisplayPort to DVI Adapter (optional)

VGA output using Mini DisplayPort to VGA Adapter (optional)

Dual-link DVI output using Mini DisplayPort to Dual-Link DVI Adapter supports 30-inch Apple Cinema HD Display (optional)

HDMI output using a third-party Mini DisplayPort to HDMI Adapter