master pop table sdram requirements are wrong. 
the fudge factor is applied to the exact cost model in the following lines:

https://github.com/SpiNNakerManchester/sPyNNaker/blob/master/spynnaker/pyNN/models/neuron/master_pop_table.py#L173-L177

But as this is meant to be the EXACT sdram, a fudge factor here makes no sense. 

But when it is removed the DSE errors on the master pop region for not having enough space. So there is obviously some other SDRAM cost that's not being taken into account that this fudge factor is hiding. 

It was found when augmenting the master pop table for self partition splitter objects. But is showable in master as well. 
diff --git a/spynnaker/pyNN/models/neuron/master_pop_table.py b/spynnaker/pyNN/models/neuron/master_pop_table.py
index 3f0294e23f..c2b9c5f6fa 100644
--- a/spynnaker/pyNN/models/neuron/master_pop_table.py
+++ b/spynnaker/pyNN/models/neuron/master_pop_table.py
@@ -153,9 +153,6 @@ _EXTRA_INFO_ENTRY_SIZE_BYTES = ctypes.sizeof(_ExtraInfoCType)
 # Base size - 2 words for size of table and address list
 _BASE_SIZE_BYTES = 8
 
-# Over-scale of estimate for safety
-_OVERSCALE = 2
-
 # A ctypes pointer to a uint32
 _UINT32_PTR = ctypes.POINTER(ctypes.c_uint32)
 
diff --git a/spynnaker/pyNN/models/neuron/synaptic_matrices.py b/spynnaker/pyNN/models/neuron/synaptic_matrices.py
index 8f1bb102da..d68e7ff698 100644
--- a/spynnaker/pyNN/models/neuron/synaptic_matrices.py
+++ b/spynnaker/pyNN/models/neuron/synaptic_matrices.py
@@ -33,9 +33,6 @@ from .key_space_tracker import KeySpaceTracker
 from .synaptic_matrix_app import SynapticMatrixApp
 
 
-# Amount to scale synapse SDRAM estimate by to make sure the synapses fit
-_SYNAPSE_SDRAM_OVERSCALE = 1.1
-
 # 1 for n_edges
 # 2 for post_vertex_slice.lo_atom, post_vertex_slice.n_atoms
 # 1 for n_synapse_types
['spynnaker/pyNN/models/neuron/master_pop_table.py', 'spynnaker/pyNN/models/neuron/synaptic_matrices.py']