igb aim not working

I been having issues on a unit I use for pfsense routing (based on FreeBSD 11.0), and recently discovered it starts random packetloss at just 2000 pps.

The network hardware is a mini pci-x intel i350 with 2 ports. It uses the igb driver.

I have tried various things but will stick to what the behaviour is at default settings.

At default msix is enabled, 4 queues (4 cpu cores), netisr will do direct dispatch.

I observe for the 2000 pps and about 70mbit throughput (download from meganz), there is about 8000 interrupts generated per queue. Which seems excessive, another observation is if I toggle 'aim' adaptive interrupt moderation, then the generated interrupts do not change at all. It is as if 'aim' is not working.

After a few days of getting nowhere, I decided to enable polling just to see if my interrupt hunch was correct, and low and behold it can handle downloading from meganz (and other high threaded sources) just fine, packet loss gone. Polling is supposedly useless on new hardware but seems not in my case.

I am aware there is fake intel cards on the market so I now suspect mine might be fake but I welcome other insights.
I thought updating the firmware/boot rom would only make a difference when using the card to boot from.
However, this thread says something different. So you might want to try that.