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Having just run the BMW Benchmark, I got roughly the following:

GPU: Just over 17 minutes CPU: Just over 3 minutes

Is this right? Surely not? That is a huge difference. Could it be that I have not configured things properly?

Ian Watts
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    Hello. Please change your title and question to be in line with this forum. What follows is standard in this situation. You may choose to rephrase your question to something like .... How can I make sure Blender is using my GPU? or ... Does Blender Support NVidia and Radeon equally? When you list your hardware in the title and question, it focuses on the hardware. BSE focuses on the use of the software and less so on the hardware. Most question that list hardware specs will be put on hold. Just a normal event. It happens once a week, loose estimate. – atomicbezierslinger Jan 25 '16 at 22:14
  • No problem - i'll edit it now – Ian Watts Jan 25 '16 at 22:19
  • You may want to see ... https://www.blender.org/manual/render/cycles/features.html and https://www.blender.org/manual/render/cycles/gpu_rendering.html – atomicbezierslinger Jan 25 '16 at 22:31
  • Thank you - for the help in phrasing the question and for pointing me in the right direction. This is going to be a steep learning curve :-) – Ian Watts Jan 25 '16 at 22:56
  • I'm voting to close this question as off-topic because it's a hardware question, and not about using Blender. – brasshat Jan 25 '16 at 23:08
  • I would not care for the results of that particular benchmark... It is not optimized to for GPU or CPU, therefore makes no sense to measure orange and apples... The tile size largely defines how efficient the rendering is going to be. Make different tests in your machine for CPU and GPU until you find the size that makes your system go smoother. Usually GPUs require tiles that are larger than 256x256 pixels vs 16 or 32 pixels for CPU –  Jan 25 '16 at 23:36
  • It is also possible that your machine's GPU is not powerful at all... ( blender does work better with Nvidia GPUS and support for AMD is limited...The multicore/multi-threading on the CPU may indeed be more efficient. Make your own tests and learn what your machine's strengths and weaknesses are... –  Jan 25 '16 at 23:38
  • Thank you all - @atomicbezierslinger actually pointed me in the right direction and I have my answer. I do wonder why hardware related questions are so frowned upon. If I had phrased the question - "Why is my CPU rendering faster than my GPU" or "Why is my rendering slow" someone would have asked me to give details of my hardware, as that has a direct bearing on the software. Is there a place to ask questions that are likely to be related to hardware as well as software. – Ian Watts Jan 26 '16 at 23:31
  • I have now changed the question and taken out all hardware related comments - of course the question now makes very little sense as it has no context, and would be much harder to answer. – Ian Watts Jan 26 '16 at 23:37
  • OK - I understand having read the help center why the stringent rules are in place, but as someone only 2 weeks into blender, and this seeming to be the place to get answers, it is all a bit overwhelming. I can understand why hardware related questions can go over the top, but you can't seperate hardware and software when problem solving, as sometimes the problem might be hardware related, as it was in my case. Thank you atomicbezierslinger for guiding me and pointing me to where I can get answers instead of just placing the question on hold, and also @cegaton for offering help too. – Ian Watts Jan 26 '16 at 23:47
  • Question about hardware (and particular brands of it) generate discussions that, for the most part, are opinion based, therefore it is very hard to give a valid or concise answer (and this is indeed a question and answer site, not a forum) Try http://blenderartists.org/forum/forumdisplay.php?44-Technical-Support where questions about hardware are rutinely asked (and redundantly answered) on a daily base. –  Jan 26 '16 at 23:58
  • Related: http://blender.stackexchange.com/questions/24272/gpu-slower-than-cpu and http://blender.stackexchange.com/questions/21321/gpu-rendering-is-equal-to-or-slower-than-cpu-rendering and http://blender.stackexchange.com/questions/42542/my-cpu-is-still-faster-than-my-gpu/42558#42558 –  Jan 26 '16 at 23:58
  • What tile sizes did you use for your tests? GPUs do better with fewer large tiles, while CPUs like lots of small tiles – gandalf3 Jan 27 '16 at 00:11
  • I tried various tile sizes but to no effect - from 64 to 512 @gandalf3 - as someone new to Blender it doesn't really matter as I am not doing the most complex stuff but it just annoys me that I have £2.5k worth of computer (that I bought for heavy photo editing which it is great at), but have since discovered Blender and I'd have been better with a PC at half the price. But you live and learn - I understand from here https://www.blender.org/manual/render/cycles/features.html why I am having this issue. Thanks all for your help. – Ian Watts Jan 27 '16 at 23:30
  • @IanWatts It's true that openCL support is still quite new and only somewhat working (probably missing many optimizations), but I'm surprised it's so much slower.. – gandalf3 Jan 27 '16 at 23:39
  • Me too @gandalf3 - I'll keep playing and see what I can do - i'll run some tests today. – Ian Watts Jan 28 '16 at 10:33
  • @IanWatts Come to think of it.. Have you tried using the split kernel? – gandalf3 Jan 28 '16 at 22:42
  • Not sure what that is. Just off to bed so will check it out tomorrow. Cheers @gandalf3 – Ian Watts Jan 29 '16 at 23:57

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