VMware i/o error occured

Hi, On an ML310e Gen8 Server, Running VMware ESXi frmo a USB stick inside it.

I plan to use the onboard raid and 4 drives for storage and an additional raid card for the virtual guest files

I added an Adapter ASR-3405 (which is supported on VMware HCL) and plan to use 4 drives off this for VM OS storage etc

Installed the HP image of VMware 4.1, 5.1u1 and 5.5 however every image gives me the same issue.

If i try to upload a file to the hard drive connected to the adaptec ASR-3405, it goes for approx 10 secs and i get an i/o error
occured

On some googling of someone getting the same error, it was suggested Intel VT-d be disabled, I did this and the error went away, i was able to successfully
upliad files to the datastore hanging off the ASR-3405.

issue is, i need VT-d as i want to direct map the onboard controller through to a storage VM, So im stuck!

Bios is up to date, Raid controller (ASR-3405) is also  up to date, well as up to date as it can be given its discontinued.

Any help would be appreciated, or hyper-v it is