diff --git a/GpuKang.cpp b/GpuKang.cpp
index 9fab56a..ef6b7e8 100644
--- a/GpuKang.cpp
+++ b/GpuKang.cpp
@@ -19,8 +19,8 @@ extern bool gGenMode; //tames generation mode
 int RCGpuKang::CalcKangCnt()
 {
 	Kparams.BlockCnt = mpCnt;
-	Kparams.BlockSize = IsOldGpu ? 512 : 256;
-	Kparams.GroupCnt = IsOldGpu ? 64 : 24;
+	Kparams.BlockSize = IsOldGpu ? BLOCK_SIZE_OLD_GPU : BLOCK_SIZE_NEW_GPU;
+	Kparams.GroupCnt = IsOldGpu ? PNT_GROUP_OLD_GPU : PNT_GROUP_NEW_GPU;
 	return Kparams.BlockSize* Kparams.GroupCnt* Kparams.BlockCnt;
 }
 
diff --git a/defs.h b/defs.h
index 0e1a3c3..a77556d 100644
--- a/defs.h
+++ b/defs.h
@@ -36,7 +36,7 @@ typedef char i8;
  
 //use different options for cards older than RTX 40xx
 #ifdef __CUDA_ARCH__
-#if __CUDA_ARCH__ < 890
+#if __CUDA_ARCH__ < 890 && __CUDA_ARCH__ != 800
 #define OLD_GPU
 #endif
 #ifdef OLD_GPU