diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index ff5760f9..62c74cc6 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -2371,6 +2371,12 @@ sub config_to_command {
 	    $ost eq 'wvista') {
 	    push @$globalFlags, 'kvm-pit.lost_tick_policy=discard';
 	    push @$cmd, '-no-hpet';
+	    #push @$cpuFlags , 'hv_vapic" if !$nokvm;  #fixme, my win2008R2 hang at boot with this
+	    push @$cpuFlags , 'hv_spinlocks=0xffff' if !$nokvm;
+	}
+
+	if ($ost eq 'win7' || $ost eq 'win8') {
+	    push @$cpuFlags , 'hv_relaxed' if !$nokvm;
 	}
     }