title: "import tensorflow as tf" ImportError: Could not find 'cudart64_90.dll'
body: <p>I am trying to learn Python and specifically TensorFlow. I have followed the instructions and have overcome several problems so far and have successfully installed TensorFlow (pip install), CUDA(9.1.85 win10), Python(3.6.3 amd64), and CUDNN(8.0 win10x64) as I have a GPU (GTX 1080) and want to be able to train networks with it. My computer has an intel i7, and Windows 10. I started with CUDA(8.0.61 win10) but it caused an error that said it needed version 9.</p>
  
  <p>When I try to test with</p>
  
  <pre><code>&gt;&gt;&gt; import tensorflow as tf
  &gt;&gt;&gt; hello = tf.constant('Hello, TensorFlow!')
  &gt;&gt;&gt; sess = tf.Session()
  &gt;&gt;&gt; print(sess.run(hello))
  </code></pre>
  
  <p>I get this error on the first line</p>
  
  <pre><code>&gt;&gt;&gt; import tensorflow as tf
  Traceback (most recent call last):
    File "C:\Program Files\Python36\lib\site-packages\tensorflow\python\platform\self_check.py", line 75, in preload_check
      ctypes.WinDLL(build_info.cudart_dll_name)
    File "C:\Program Files\Python36\lib\ctypes\__init__.py", line 348, in __init__
      self._handle = _dlopen(self._name, mode)
  OSError: [WinError 126] The specified module could not be found
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
    File "&lt;pyshell#0&gt;", line 1, in &lt;module&gt;
      import tensorflow as tf
    File "C:\Program Files\Python36\lib\site-packages\tensorflow\__init__.py", line 24, in &lt;module&gt;
      from tensorflow.python import *
    File "C:\Program Files\Python36\lib\site-packages\tensorflow\python\__init__.py", line 49, in &lt;module&gt;
      from tensorflow.python import pywrap_tensorflow
    File "C:\Program Files\Python36\lib\site-packages\tensorflow\python\pywrap_tensorflow.py", line 30, in &lt;module&gt;
      self_check.preload_check()
    File "C:\Program Files\Python36\lib\site-packages\tensorflow\python\platform\self_check.py", line 82, in preload_check
      % (build_info.cudart_dll_name, build_info.cuda_version_number))
  ImportError: Could not find 'cudart64_90.dll'. TensorFlow requires that this DLL be installed in a directory that is named in your %PATH% environment variable. Download and install CUDA 9.0 from this URL: https://developer.nvidia.com/cuda-toolkit
  </code></pre>
  
  <p>How can I fix this?</p>
  
  <p>PS: I have read all other questions about this on this site and have also read the <a href="https://www.tensorflow.org/install/install_windows#common_installation_problems" rel="nofollow noreferrer">common problems</a> page. I'm sorry the errors don't seem to match my specific problem but obviously I am lost here.</p>