You may not need another RAID controller, but you most likely won't achieve that level of write performance using 4 of those hard disks. You may be able to exceed the results achived at http://www.extremetech.com/article2/0,2845,2334985,00.a..., but it would still be way below your requirements.
Reading http://www.tomshardware.com/reviews/ich10r-sb750-780a,2... might help you decide on the optimal solution (they used SSD drives). As you can see, the ICH10R performs quite well. Even a RAID 5 configuration using 3 SSDs would be fine. You should be mainly interested in the minimum write performance.
Four 15K SAS drives on a caching RAID controller with BBS might meet your requirements, but it still would be significantly slower than SSDs.