4 Replies Latest reply on Jul 20, 2011 9:10 AM by himanshu.gautam

    HD 6790 double precision?



      I have a Sapphire HD 6790 card which according to the AMD Specs does  have double precision capabilites:


      I installed acmlgpu1.1.2, and Catlyst 11.6. When I execute "GPGPUexamples/Info.exe" I get in the gpu part:

          Type:                            CALtarget(17) (unknown type)
          Revision:                          20
          Maximum resource 1D width:       16384
          Maximum resource 2D width:       16384
          Maximum resource 2D height:      16384
          Local GPU RAM:                   1024 megabytes
          Uncached remote GPU memory:      1788 megabytes
          Cached remote GPU memory:         508 megabytes
          GPU device clock rate:            840 megahertz
          GPU memory clock rate:           1050 megahertz
          Wavefront size:                    64
          Number of SIMDs:                   10
          Number of shader engines:           2
          double precision:                Not supported
          local data share:                Supported
          global data share:               Supported
          global GPR:                      Supported
          compute shader:                  Supported
          memexport:                       Supported
          calResCreate pitch alignment:     256 data elements
          calResCreate address alignment:   256 bytes
          Unaligned Access Views (UAVs):     12
          3D program grid:                 Supported


      Note the "not supported" for "double precision". Running "/gfortran/examples/performance/time_dgemm.exe" I get:

      "Warning:  no suitable GPUs found for double-precision GPGPU operations."

      What's going on here?

      Best regards,


        • HD 6790 double precision?

          I suspect that is a serious copy-paste mistake. Only the high-end GPUs support DP precision. When this is the case, compute power is always listed seperately for SP and DP. HD 6790 does not support DP, even if it is listed on the website. A dire mistake indeed.

          HD5850, HD5870, HD5970, HD6950, HD6970, HD6990 are the only graphics cards that support DP operations.