diff --git a/projects/ad9671_fmc/a5gt/system_constr.sdc b/projects/ad9671_fmc/a5gt/system_constr.sdc
index 824fab80f..9a072102f 100644
--- a/projects/ad9671_fmc/a5gt/system_constr.sdc
+++ b/projects/ad9671_fmc/a5gt/system_constr.sdc
@@ -1,32 +1,29 @@
 
 create_clock -period "10.000 ns" -name n_clk_100m [get_ports {sys_clk}]
-create_clock -period "4.000 ns" -name n_clk_250m [get_ports {ref_clk}]
+create_clock -period "12.500 ns" -name n_clk_ref [get_ports {ref_clk}]
 create_clock -period "8.000 ns" -name n_eth_rx_clk_125m [get_ports {eth_rx_clk}]
 create_clock -period "8.000 ns" -name n_eth_tx_clk_125m [get_nets {eth_tx_clk}]
 
 derive_pll_clocks
 derive_clock_uncertainty
 
-set clk_100m    [get_clocks {i_system_bd|sys_pll|altera_pll_i|general[0].gpll~PLL_OUTPUT_COUNTER|divclk}]
-set clk_166m    [get_clocks {i_system_bd|sys_pll|altera_pll_i|general[1].gpll~PLL_OUTPUT_COUNTER|divclk}]
-set clk_125m    [get_clocks {i_system_bd|sys_pll|altera_pll_i|general[2].gpll~PLL_OUTPUT_COUNTER|divclk}]
-set clk_25m     [get_clocks {i_system_bd|sys_pll|altera_pll_i|general[3].gpll~PLL_OUTPUT_COUNTER|divclk}]
-set clk_2m5     [get_clocks {i_system_bd|sys_pll|altera_pll_i|general[4].gpll~PLL_OUTPUT_COUNTER|divclk}]
-set clk_rxlink  [get_clocks {i_system_bd|sys_jesd204b_s1_pll|altera_pll_i|general[0].gpll~PLL_OUTPUT_COUNTER|divclk}]
+set clk_100m     {i_system_bd|sys_pll|altera_pll_i|general[0].gpll~PLL_OUTPUT_COUNTER|divclk}
+set clk_166m     {i_system_bd|sys_pll|altera_pll_i|general[1].gpll~PLL_OUTPUT_COUNTER|divclk}
+set clk_125m     {i_system_bd|sys_pll|altera_pll_i|general[2].gpll~PLL_OUTPUT_COUNTER|divclk}
+set clk_25m      {i_system_bd|sys_pll|altera_pll_i|general[3].gpll~PLL_OUTPUT_COUNTER|divclk}
+set clk_2m5      {i_system_bd|sys_pll|altera_pll_i|general[4].gpll~PLL_OUTPUT_COUNTER|divclk}
+set clk_rxlink   {i_system_bd|sys_jesd204b_s1_pll|altera_pll_i|general[0].gpll~PLL_OUTPUT_COUNTER|divclk}
+
+set_clock_groups -asynchronous -group [get_clocks {n_clk_ref} ]
+set_clock_groups -asynchronous -group [get_clocks {n_clk_100m} ]
+set_clock_groups -asynchronous -group [get_clocks {n_eth_rx_clk_125m} ]
+set_clock_groups -asynchronous -group [get_clocks {n_eth_tx_clk_125m} ]
+set_clock_groups -asynchronous -group [get_clocks $clk_100m ]
+set_clock_groups -asynchronous -group [get_clocks $clk_166m ]
+set_clock_groups -asynchronous -group [get_clocks $clk_125m ]
+set_clock_groups -asynchronous -group [get_clocks $clk_25m ]
+set_clock_groups -asynchronous -group [get_clocks $clk_2m5 ]
+set_clock_groups -asynchronous -group [get_clocks $clk_rxlink ]
 
 set_false_path -from {sys_resetn} -to *
-set_false_path -from $clk_100m -to $clk_166m
-set_false_path -from $clk_100m -to $clk_rxlink
-set_false_path -from $clk_166m -to $clk_100m
-set_false_path -from $clk_166m -to $clk_rxlink
-set_false_path -from $clk_rxlink -to $clk_100m
-set_false_path -from $clk_rxlink -to $clk_166m
-
-set_false_path -from $clk_125m -to $clk_25m
-set_false_path -from $clk_125m -to $clk_2m5
-set_false_path -from $clk_25m -to $clk_125m
-set_false_path -from $clk_25m -to $clk_2m5
-set_false_path -from $clk_2m5 -to $clk_125m
-set_false_path -from $clk_2m5 -to $clk_25m
-
-
+set_false_path -from  * -to {sys_resetn}
diff --git a/projects/ad9671_fmc/a5gt/system_timing.tcl b/projects/ad9671_fmc/a5gt/system_timing.tcl
index e1f355d44..a62293897 100644
--- a/projects/ad9671_fmc/a5gt/system_timing.tcl
+++ b/projects/ad9671_fmc/a5gt/system_timing.tcl
@@ -1,3 +1,16 @@
 
-report_timing -detail path_only -npaths 20 -file timing_impl.log
-  
+set worst_path [get_timing_paths -npaths 1 -setup]
+foreach_in_collection path $worst_path {
+  set slack [get_path_info $path -slack]
+}
+
+if {$slack > 0} {
+  set worst_path [get_timing_paths -npaths 1 -hold]
+  foreach_in_collection path $worst_path {
+    set slack [get_path_info $path -slack]
+  }
+}
+
+if {$slack < 0} {
+  use_this_invalid_command_to_crash
+}