downgraded cuda to 7.5
diff --git a/.travis.yml b/.travis.yml
index 4609d27..0a83c51 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,22 +6,22 @@
 language: cpp
 matrix:
   include:
-   # - os: linux
-   #   compiler: gcc
-   #   addons:
-   #     apt:
-   #       sources: ['ubuntu-toolchain-r-test']
-   #       packages: ['g++-4.8']
-   #   env: COMPILER=g++-4.8
+    - os: linux
+      compiler: gcc
+      addons:
+        apt:
+          sources: ['ubuntu-toolchain-r-test']
+          packages: ['g++-4.8']
+      env: COMPILER=g++-4.8
 
-   # - os: linux
-   #   compiler: gcc
-   #   addons:
-   #     apt:
-   #       sources: ['ubuntu-toolchain-r-test']
-   #       packages: ['g++-4.9']
-   #   env: COMPILER=g++-4.9
-   #
+    - os: linux
+      compiler: gcc
+      addons:
+        apt:
+          sources: ['ubuntu-toolchain-r-test']
+          packages: ['g++-4.9']
+      env: COMPILER=g++-4.9
+   
     - os: linux
       compiler: gcc
       addons:
@@ -33,15 +33,13 @@
 install:
   - sudo apt-get install libprotobuf-dev protobuf-compiler libatlas-base-dev libgoogle-glog-dev libgtest-dev liblmdb-dev libleveldb-dev libsnappy-dev python-dev python-pip libiomp-dev libopencv-dev nvidia-cuda-toolkit libpthread-stubs0-dev cmake
   - pip install numpy
-  #- curl --retry 10 --retry-max-time 120 -L "https://launchpad.net/gcc-arm-embedded/5.0/5-2016-q2-update/+download/gcc-arm-none-eabi-5_4-2016q2-20160622-linux.tar.bz2" | tar xfj -
-  #- export PATH=$PWD/gcc-arm-none-eabi-5_4-2016q2/bin:$PATH
-  - wget http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1404/x86_64/cuda-repo-ubuntu1404_8.0.44-1_amd64.deb
-  - sudo dpkg -i cuda-repo-ubuntu1404_8.0.44-1_amd64.deb
+  - wget http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1404/x86_64/cuda-repo-ubuntu1404_7.5-18_amd64.deb
+  - sudo dpkg -i cuda-repo-ubuntu1404_7.5-18_amd64.deb
   - sudo apt-get update
   - sudo apt-get install cuda
 
 script:
-  - mkdir build && cd build && export CXX=$COMPILER && cmake .. -DCMAKE_VERBOSE_MAKEFILE=ON && make
+  - mkdir build && cd build && export CXX=$COMPILER && cmake .. -DCMAKE_VERBOSE_MAKEFILE=ON && make CXX=$COMPILER
 
 # safelist
 branches: