[doc] updated readme

README.md

@@ -10,21 +10,23 @@ See paper: "Detection and Accurate Localization of Circular Fiducials under High
 Marker library
 ---------
 
-Markers to print are located [here](markersToPrint). 
+Markers to print are located [here](markersToPrint).
 
 **WARNING**
 Please respect the provided margins. The reported detection rate and localization accuracy are valid with completely planar support: be careful not to use bent support (e.g. corrugated sheet of paper).
 
 The four rings CCTags will be available soon.
 
+CCTags requires either CUDA 8.0 and newer or CUDA 7.0 (CUDA 7.5 builds are known to have runtime errors on some devices including the GTX980Ti). The device must have at least compute capability 3.5.
+
 Check your graphic card CUDA compatibility [here](https://github.com/tpruvot/ccminer/wiki/Compatibility).
 
 Building
 --------
 
 See [BUILD](BUILD.md) text file.
 
-Continuous integration: 
+Continuous integration:
  - [![Build Status](https://travis-ci.org/alicevision/CCTag.svg?branch=master)](https://travis-ci.org/alicevision/CCTag) master branch.
  - [![Build Status](https://travis-ci.org/alicevision/CCTag.svg?branch=develop)](https://travis-ci.org/alicevision/CCTag) develop branch.
 
@@ -34,7 +36,7 @@ Running
 Once compiled, you might want to run the CCTag detection on a sample image:
 ```bash
 $ build/src/detection -n 3 -i sample/01.png
-``` 
+```
 For the library interface, see [ICCTag.hpp](src/cctag/ICCTag.hpp).
 
 License