diff --git a/apps/nccl/src/allreduce.hpp b/apps/nccl/src/allreduce.hpp
index 7a2cd4a..a14dfbc 100644
--- a/apps/nccl/src/allreduce.hpp
+++ b/apps/nccl/src/allreduce.hpp
@@ -850,7 +850,7 @@ cudaError_t allreduce(T* buff, T* scratch, T* resultBuff, mscclpp::DeviceHandle<
                                                          flag++);
 #endif
   } else {
-    int nBlocks = 5*(nRanksPerNode - 1);
+    int nBlocks = 8 * (nRanksPerNode - 1);
     int nThreadsPerBlock = 512;
     if (hieAllred && worldSize >= 8) {
 	nBlocks = 20;
diff --git a/apps/nccl/src/common.hpp b/apps/nccl/src/common.hpp
index ca2c272..a6056ea 100644
--- a/apps/nccl/src/common.hpp
+++ b/apps/nccl/src/common.hpp
@@ -17,7 +17,7 @@ constexpr int NRANKS1_PER_NODE = 4;
 constexpr int NRANKS_PER_NODE = 8;
 constexpr int NPEERS = 7;
 
-constexpr int SCRATCH_SIZE = 2 * 1024 * 1024 * 70;  // double buffer * 35 thread-blocks * 8 ranks * 256KB = 70MB
+constexpr int SCRATCH_SIZE = 2 * 1024 * 1024 * 112;  // double buffer * 56 thread-blocks * 8 ranks * 256KB = 112MB
 
 __device__ mscclpp::DeviceSyncer deviceSyncer;