TD-W8970 is a 300 Mbps wireless modem router, which we can see from the introduction on TP-LINK official website. http://www.tp-link.com/en/products/details/?categoryid=&model=TD-W8970

For TD-W8980, also we can see in http://www.tp-link.com/en/products/details/?categoryid=&model=TD-W8980 :Simultaneous 2.4GHz 300Mbps and 5GHz 300Mbps connections for 600Mbps of total available bandwidth

Hope this helps :)

thanks for your reply , yes the website said it a 300Mbps wireless modem router
but if you test 8970 with RF analyzing tools like inssider it shows the bandwidth at 450Mbps. further tplink said TL-WR1043ND is a 300Mbps Wireless N Gigabit Router but it has a Speed Boost mode which can increase the speed up to 450Mbps
TP-LINK TL-WDR4900 has 450Mbps speed at 2.4Ghz and use the same chpset in TD-8970 , AR9381 Atheros 3x3:3 MIMO BGN

I want to know if tplink has made software limitation on this product or the hardware can not handle 450Mbps ?