diff --git a/spinn_machine/virtual_machine.py b/spinn_machine/virtual_machine.py
index 12c34d9c..49d15920 100644
--- a/spinn_machine/virtual_machine.py
+++ b/spinn_machine/virtual_machine.py
@@ -29,20 +29,17 @@
 
 
 def virtual_machine(
-        width: int, height: int, n_cpus_per_chip: Optional[int] = None,
-        validate: bool = True):
+        width: int, height: int, validate: bool = True):
     """
     Create a virtual SpiNNaker machine, used for planning execution.
 
     :param int width: the width of the virtual machine in chips
     :param int height: the height of the virtual machine in chips
-    :param int n_cpus_per_chip: The number of CPUs to put on each chip
     :param bool validate: if True will call the machine validate function
     :returns: a virtual machine (that cannot execute code)
     :rtype: ~spinn_machine.Machine
     """
-
-    factory = _VirtualMachine(width, height, n_cpus_per_chip, validate)
+    factory = _VirtualMachine(width, height, validate)
     return factory.machine
 
 
@@ -67,9 +64,10 @@ class _VirtualMachine(object):
     ORIGIN = "Virtual"
 
     def __init__(
-            self, width: int, height: int,
-            n_cpus_per_chip: Optional[int] = None, validate: bool = True):
+            self, width: int, height: int, validate: bool = True):
         version = MachineDataView.get_machine_version()
+        version.verify_size(height, width)
+        max_cores = version.max_cores_per_chip
         self._n_router_entries = version.n_router_entries
         self._machine = version.create_machine(
             width, height, origin=self.ORIGIN)
@@ -104,17 +102,11 @@ def __init__(
         # If there are no wrap arounds, and the the size is not 2 * 2,
         # the possible chips depend on the 48 chip board's gaps
         configured_chips: Dict[XY, Tuple[XY, int]] = dict()
-        if n_cpus_per_chip is None:
-            for eth in ethernet_chips:
-                for (xy, n_cores) in self._machine.get_xy_cores_by_ethernet(
-                        *eth):
-                    if xy not in unused_chips:
-                        configured_chips[xy] = (eth, n_cores)
-        else:
-            for eth in ethernet_chips:
-                for xy in self._machine.get_xys_by_ethernet(*eth):
-                    if xy not in unused_chips:
-                        configured_chips[xy] = (eth, n_cpus_per_chip)
+        for eth in ethernet_chips:
+            for (xy, n_cores) in self._machine.get_xy_cores_by_ethernet(
+                    *eth):
+                if xy not in unused_chips:
+                    configured_chips[xy] = (eth, min(n_cores, max_cores))
 
         # for chip in self._unreachable_outgoing_chips:
         #    configured_chips.remove(chip)
diff --git a/unittests/test_virtual_machine.py b/unittests/test_virtual_machine.py
index 353fd256..936b3324 100644
--- a/unittests/test_virtual_machine.py
+++ b/unittests/test_virtual_machine.py
@@ -126,6 +126,8 @@ def test_version_5_8_by_8(self):
         self.assertFalse((0, 4) in list(vm.chip_coordinates))
         count = sum(1 for _chip in vm.chips for _link in _chip.router.links)
         self.assertEqual(240, count)
+        count = sum(_chip.n_processors for _chip in vm.chips)
+        self.assertEqual(count, 856)
 
     def test_version_5_12_by_12(self):
         set_config("Machine", "version", 5)
@@ -167,16 +169,19 @@ def test_version_5_hole2(self):
         self.assertEqual(48, len(list(vm.local_xys)))
         self.assertEqual((0, 4), vm.get_unused_xy())
 
-    def test_new_vm_with_monitor(self):
+    def test_new_vm_with_max_cores(self):
         set_config("Machine", "version", 2)
         n_cpus = 13
-        vm = virtual_machine(2, 2, n_cpus_per_chip=n_cpus, validate=True)
+        set_config("Machine", "max_machine_core", n_cpus)
+        vm = virtual_machine(2, 2, validate=True)
         _chip = vm[1, 1]
         self.assertEqual(n_cpus, _chip.n_processors)
         self.assertEqual(n_cpus - 1, _chip.n_user_processors)
         self.assertEqual(1, _chip.n_monitor_processors)
         self.assertEqual(n_cpus - 1, len(list(_chip.user_processors)))
         self.assertEqual(1, len(list(_chip.monitor_processors)))
+        count = sum(_chip.n_processors for _chip in vm.chips)
+        self.assertEqual(count, 4 * n_cpus)
 
     def test_iter_chips(self):
         set_config("Machine", "version", 2)