Sorry you are running into this problem. Could you possibily list the driver name and version that you have loaded on these two network adapters? There were some changes to RSS between NDIS 6.20 and previous NDIS 6.x versions, and this might be the cause. Thank you for using Intel Ethernet.
Message about true NDIS 6.20 receive-side scaling when configuring a team has an explanation, but does not answer all your questions. The Intel(R) PRO/1000 PT Quad Port Server adapter does notsupport true NDIS 6.20 Receive-Side Scaling. The Intel(R) PRO/1000 ET Quad Port Server does support support true NDIS 6.20 Receive-Side Scaling. Either adapter supports RSS in Windows Server 2008 R2; however, because the support is different in each adapter, they cannot do RSS when teamed together.
If you disable RSS on the team, you will take a performance hit. The difference in performance between teaming the 8 ports without RSS versus teaming just 4 ports with RSS would have to be tested in your system with examples of your real-time traffic.
If you need the bandwidth of 8 gigabit ports in a Link Aggregation Team, then your best bet is to use two adapters of the same type instead of mixing the adapters.
I hope this helps you.