diff --git a/litex_boards/platforms/qmtech_artix7_fbg484.py b/litex_boards/platforms/qmtech_artix7_fbg484.py
index 3be25ac..5fa2f5b 100644
--- a/litex_boards/platforms/qmtech_artix7_fbg484.py
+++ b/litex_boards/platforms/qmtech_artix7_fbg484.py
@@ -39,29 +39,29 @@ _io = [
     # MT41K128M16JT-125K
     ("ddram", 0,
         Subsignal("a", Pins("A15 D14 A14 D15 E14 F14 E13 C13 E16 B13 C17 F13 F16 A13"),
-            IOStandard("SSTL135")),
-        Subsignal("ba",    Pins("D16 E17 B15"), IOStandard("SSTL135")),
-        Subsignal("ras_n", Pins("B17"), IOStandard("SSTL135")),
-        Subsignal("cas_n", Pins("B16"), IOStandard("SSTL135")),
-        Subsignal("we_n",  Pins("A16"), IOStandard("SSTL135")),
+            IOStandard("SSTL15")),
+        Subsignal("ba",    Pins("D16 E17 B15"), IOStandard("SSTL15")),
+        Subsignal("ras_n", Pins("B17"), IOStandard("SSTL15")),
+        Subsignal("cas_n", Pins("B16"), IOStandard("SSTL15")),
+        Subsignal("we_n",  Pins("A16"), IOStandard("SSTL15")),
         # cs_n is hardwired on the board
-        #Subsignal("cs_n",  Pins(""), IOStandard("SSTL135")),
-        Subsignal("dm", Pins("F19 D20"), IOStandard("SSTL135")),
+        #Subsignal("cs_n",  Pins(""), IOStandard("SSTL15")),
+        Subsignal("dm", Pins("F19 D20"), IOStandard("SSTL15")),
         Subsignal("dq", Pins(
             "B20 A18 A20 D19 A19 C18 C19 E19 C20 D22 D21 E21 C22 G21 B22 E22"),
-            IOStandard("SSTL135"),
+            IOStandard("SSTL15"),
             Misc("IN_TERM=UNTUNED_SPLIT_40")),
         Subsignal("dqs_p", Pins("F18 B21"),
-            IOStandard("DIFF_SSTL135"),
+            IOStandard("DIFF_SSTL15"),
             Misc("IN_TERM=UNTUNED_SPLIT_40")),
         Subsignal("dqs_n", Pins("E18 A21"),
-            IOStandard("DIFF_SSTL135"),
+            IOStandard("DIFF_SSTL15"),
             Misc("IN_TERM=UNTUNED_SPLIT_40")),
-        Subsignal("clk_p", Pins("C14"), IOStandard("DIFF_SSTL135")),
-        Subsignal("clk_n", Pins("C15"), IOStandard("DIFF_SSTL135")),
-        Subsignal("cke",   Pins("B18"), IOStandard("SSTL135")),
-        Subsignal("odt",   Pins("D17"), IOStandard("SSTL135")),
-        Subsignal("reset_n", Pins("F15"), IOStandard("SSTL135")),
+        Subsignal("clk_p", Pins("C14"), IOStandard("DIFF_SSTL15")),
+        Subsignal("clk_n", Pins("C15"), IOStandard("DIFF_SSTL15")),
+        Subsignal("cke",   Pins("B18"), IOStandard("SSTL15")),
+        Subsignal("odt",   Pins("D17"), IOStandard("SSTL15")),
+        Subsignal("reset_n", Pins("F15"), IOStandard("SSTL15")),
         Misc("SLEW=FAST"),
     ),
 ]
diff --git a/litex_boards/platforms/qmtech_artix7_fgg676.py b/litex_boards/platforms/qmtech_artix7_fgg676.py
index 6a0ce64..73156e3 100644
--- a/litex_boards/platforms/qmtech_artix7_fgg676.py
+++ b/litex_boards/platforms/qmtech_artix7_fgg676.py
@@ -39,29 +39,29 @@ _io = [
     # MT41K128M16JT-125K
     ("ddram", 0,
         Subsignal("a", Pins("E17 G17 F17 C17 G16 D16 H16 E16 H14 F15 F20 H15 C18 G15"),
-            IOStandard("SSTL135")),
-        Subsignal("ba",    Pins("B17 D18 A17"), IOStandard("SSTL135")),
-        Subsignal("ras_n", Pins("A19"), IOStandard("SSTL135")),
-        Subsignal("cas_n", Pins("B19"), IOStandard("SSTL135")),
-        Subsignal("we_n",  Pins("A18"), IOStandard("SSTL135")),
+            IOStandard("SSTL15")),
+        Subsignal("ba",    Pins("B17 D18 A17"), IOStandard("SSTL15")),
+        Subsignal("ras_n", Pins("A19"), IOStandard("SSTL15")),
+        Subsignal("cas_n", Pins("B19"), IOStandard("SSTL15")),
+        Subsignal("we_n",  Pins("A18"), IOStandard("SSTL15")),
         # cs_n is hardwired on the board
-        #Subsignal("cs_n",  Pins(""), IOStandard("SSTL135")),
-        Subsignal("dm", Pins("A22 C22"), IOStandard("SSTL135")),
+        #Subsignal("cs_n",  Pins(""), IOStandard("SSTL15")),
+        Subsignal("dm", Pins("A22 C22"), IOStandard("SSTL15")),
         Subsignal("dq", Pins(
             "D21 C21 B22 B21 D19 E20 C19 D20 C23 D23 B24 B25 C24 C26 A25 B26"),
-            IOStandard("SSTL135"),
+            IOStandard("SSTL15"),
             Misc("IN_TERM=UNTUNED_SPLIT_40")),
         Subsignal("dqs_p", Pins("B20 A23"),
-            IOStandard("DIFF_SSTL135"),
+            IOStandard("DIFF_SSTL15"),
             Misc("IN_TERM=UNTUNED_SPLIT_40")),
         Subsignal("dqs_n", Pins("A20 A24"),
-            IOStandard("DIFF_SSTL135"),
+            IOStandard("DIFF_SSTL15"),
             Misc("IN_TERM=UNTUNED_SPLIT_40")),
-        Subsignal("clk_p", Pins("F18"), IOStandard("DIFF_SSTL135")),
-        Subsignal("clk_n", Pins("F19"), IOStandard("DIFF_SSTL135")),
-        Subsignal("cke",   Pins("E18"), IOStandard("SSTL135")),
-        Subsignal("odt",   Pins("G19"), IOStandard("SSTL135")),
-        Subsignal("reset_n", Pins("H17"), IOStandard("SSTL135")),
+        Subsignal("clk_p", Pins("F18"), IOStandard("DIFF_SSTL15")),
+        Subsignal("clk_n", Pins("F19"), IOStandard("DIFF_SSTL15")),
+        Subsignal("cke",   Pins("E18"), IOStandard("SSTL15")),
+        Subsignal("odt",   Pins("G19"), IOStandard("SSTL15")),
+        Subsignal("reset_n", Pins("H17"), IOStandard("SSTL15")),
         Misc("SLEW=FAST"),
     ),
 ]