View Full Version : Configuring Samsung 27inch S27A850T switchresx

9th September 2012, 12:21 PM
I'm trying to configure my Samsung S27A850T using SwitchResX, I've followed a very useful post here and using the SwitchResX attempted to configure a new resolution 2560 x 1440 @ 60hz, but failed to get it to work.

Computer Info:

Powerbook Pro i7 late 2010, Software Mac OS X Lion 10.7.4
Graphics NVIDIA GeForce GT 330M 512 MB


Samsung 27Inch S27A850T, optimal resolution: 2650 x 1440 @60hz

SwitchResX EDID:

Monitor Description blocks:
Descriptor #0 - Timing definition:
Mode = 2560 x 1440 @ 59.951Hz
Pixel Clock............. 241.50 MHz Non-Interlaced

Horizontal Vertical
Active.................. 2560 pixels 1440 lines
Front Porch............. 48 pixels 3 lines
Sync Width.............. 32 pixels 5 lines
Back Porch.............. 80 pixels 33 lines
Blanking................ 160 pixels 41 lines
Total................... 2720 pixels 1481 lines
Scan Rate............... 88.787 kHz 59.951 Hz

Image Size.............. 518 mm 324 mm
Border.................. 0 pixels 0 lines

Sync: Digital separate with
* Negative vertical polarity
* Positive horizontal polarity

Descriptor #1 - Monitor limits:
Horizontal frequency range.......30-90 kHz
Vertical frequency range.........56-75 Hz
Maximum bandwidth unspecified

I've entered these value as a custom entry into the Custom Entry of the SwitchResX, rebooted and they are "Not Active - Invalid". Can anyone help or does anyone know the correct values ? If I found the solution I'll post it here.

Thanks in advance for any help/suggestions you may have.

(This reminds me of the early Linux days ... )

9th September 2012, 02:35 PM
What resolution are you stuck on? A single DVI link is only capable of 1920x1080. You will need a mini display port or dual link DVI cable to go higher than that.

Also, do you know what the native resolution of the monitor actually is?

9th September 2012, 03:14 PM
Screen Resolution as stated by OP is 2560 x 1440

Patrick01 where did you get that screen from? Is it better than the Dell U2711?

9th September 2012, 04:15 PM
Not so... I have 2007 Macbook Pro on DVI with Apple cinema display at 1920X1200

9th September 2012, 05:07 PM
I've been able to get my resolutions to work even with the VGA adaptor in the Thunderbolt port of my iMac. I also have DVI and HDMI adaptors, all of which you can get cheaply from eBay.

Usually your model should be listed in the Display options.

I did have problems with an older display however on my current 27" iMac, which is quite irritating as the same monitor worked normally with my older 24" iMac without problems.

Sometimes you wish Apple would let you get into the settings, like they do in more technical areas of the Mac, perhaps by holding down the option key as you click on the particular Preference settings.

9th September 2012, 06:24 PM
1920x1080, 1920x1200... Those who know, know what I meant. That is the highest resolution you can get with a single link DVI cable, VGA does not have the limitations of DVI, but is an analogue signal with no capability for sound in the one cable. As I stated you will need a dual link DVI cable, or display port, VGA will do it at a stretch but the picture quality will not be as good and there is no possibility for sound in the one cable.

10th September 2012, 03:51 PM
The only question I might ask is... why not use OSX's built in management with the samsung? Surely you would get the desired resolution, given that your MBP can drive it.

10th September 2012, 04:24 PM
This may be an issue of assuming the inbuilt management can't do it where this is a hardware issue. Of course easily resolved with the right adapter (Dual link DVI).

10th September 2012, 09:56 PM
I just got a Dell U2711. It's the same deal you will need one of these to use the full res of your screen:

Mini DisplayPort to Dual-Link DVI Adapter - Apple Store (Australia) (http://store.apple.com/au/product/MB571Z/A/mini-displayport-to-dual-link-dvi-adapter)

14th September 2012, 07:11 AM
Thank you for your help, yes the solution was the Mini DisplayPort to Dual-Link DVI Adapter, it now runs at 2560 x 1440 with the stated configuration.

14th September 2012, 07:16 AM
I can not compare it to the dell U2711 as I've not tried it, but it is the best screen I've tried, I use it for coding, it replaces my apple 23inch cinema screen and it's a big improvement. I am getting issues with the screen on wake up, but I think that my display port is damaged and causing the issue.

5th March 2013, 04:56 PM
Thank you for your help, yes the solution was the Mini DisplayPort to Dual-Link DVI Adapter, it now runs at 2560 x 1440 with the stated configuration.

And How is it working?
Do you have some trouble?