Video gets stuck on DS Control Point Client Station

Hello,

I am using PELCO IXE31 cameras along with PELCO Esprit 5230 in my CCTV system. I am running my NVS on Windows 7 Virtual Machine built on vSphere hypervisor with the following specs.

CPU: 12 virtual CPUs

RAM: 8GB

HDD: 100GB vdisk (for Win7), 800GB vdisk (for Recording), 2TB Fiber Channel SAN Volume (for Recording)

Network: 1Gbps through vSwitch

There are total 6 cameras in my CCTV system (4 x IXE31 & 2 x 5230). The client also has win7 directly installed without any hypervisor & hardware is also very powerful:

hp Z800

CPU: Intel Xeon X5560

RAM: 28GB

GPU: 12GB NVDIA TITAN

HDD: 256GB SSD

Network: 1Gbps

All cameras are set to their best output (12Mbps, 2048x1536, 30fps for IXE31 & 8Mbps, 1920x1080, 30fps for Esprit 5230)

I wonder still the video is flickering at the client. Any resolution?