CPU utilization is not evenly distributed on 4 numa system

It's quite often I see 2 numa node cpu's at 100% utilization the the remaining numa cpu's at around 20% or less average utilization. There are 160 visible schedulers in dm_os_schedulers dmv. The system specs is listed below.

What could be the cause of this?

Thank you

CounterNameCounterValue
IsClusteredClustered
ClusterNodeCnt2
SystemManufacturerSystem Manufacturer: 'Dell Inc.', System Model: 'PowerEdge R910'.
ProcessorInfoIntel(R) Xeon(R) CPU E7- 4850  @ 2.00GHz
CpuCount80
HyperthreadRatio20
TotalPhysicalMemoryMB1,048,562.82
MaxDegreeOfParallelism4
ClrEnabled1
xp_cmdshell1
DefaultTraceEnabled1
ProductVersion11.0.2100.60
VersionMicrosoft SQL Server 2012 - 11.0.2100.60 (X64)  |  Feb 10 2012 19:39:15  |  Copyright (c) Microsoft Corporation |  Enterprise Edition: Core-based Licensing (64-bit) on Windows NT 6.1 <X64> (Build 7601: Service Pack 1) | 
ProductLevelRTM

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Gokhan Varol