Dropped packets by Wireshark/Dumpcap/WinDump

Hello, We are trying to record some iSCSI traffic using Wireshark, and was consistently seeing dropped packets. We are running with a 1G buffer size, and rotating 5 files with 1G file size as well. The data is being saved to a RAMDisk, and the TEMP environment variables have also been changed to use the Ramdisk.

Switched to using dumpcap straight, and with larger buffer sizes like wireshark. Same with winDump.

The machine is a 2.4GHz, 12 core, machine, and CPU usage when these numbers were recorded is about 14% max, including the dumppcap. The machine has about 72G of memory, 40 of which is being used for the Ramdisk, and about 20 is unused when these numbers were recorded.

I am positive we are doing something wrong here, or missing something really obvious. Can someone please point us in the right direction?

Here is the dumpcap output

C:\Program Files\Wireshark>dumpcap.exe -i 2 -i 3 -B 1024 -b files:5 -w F:\Trace\2.pcap
dumpcap: Ring buffer requested, but no maximum capture file size or duration were specified.
Capturing on 2 interfaces
File: F:\Trace\2_00001_20151207074008.pcap
Packets captured: 537560
Packets received/dropped on interface \Device\NPF_{42D93B77-D5B2-4FAD-8901-E7C54D63ECAD}: 421222/722498 (36.8%)
Packets received/dropped on interface \Device\NPF_{B0462921-3F8D-44A0-B828-7FDF0FD0AB9B}: 653570/556621 (54.0%)

F:\ is the RAMDisk.

The current output on the machines is about 1.5 Gbps on each interface being captured. We see the same behavior even when we try to use a single interface

C:\Program Files\Wireshark>dumpcap.exe -i 2 -B 1024 -b files:5 -w F:\Trace\2.pcap
dumpcap: Ring buffer requested, but no maximum capture file size or duration were specified.
Capturing on \Device\NPF_{42D93B77-D5B2-4FAD-8901-E7C54D63ECAD}
File: F:\Trace\2_00001_20151207074218.pcap
Packets captured: 419766
Packets received/dropped on interface \Device\NPF_{42D93B77-D5B2-4FAD-8901-E7C54D63ECAD}: 419766/587700 (41.7%)

With Windump, this is what we see:

F:\WinDump>WinDump.exe -n -i \Device\NPF_{42D93B77-D5B2-4FAD-8901-E7C54D63ECAD} -s0 -C 1024 -W 5 -B 2048576 -w capture.pcap -p -U
WinDump.exe: listening on \Device\NPF_{42D93B77-D5B2-4FAD-8901-E7C54D63ECAD}

2980237 packets captured
4512223 packets received by filter
1449839 packets dropped by kernel