yeah i know 8+1 is 4 channels but those are usually more safer then that of 4+1's in general, some been known to go poof on stock Values and being a Quad Core or higher CPU, the Biostar is using a Analog Mosfet which can take like 300watts of power on the CPU alone before anything happens. but they run extremely warm apparently to the touch on the heatsink.
both are good companies, and such Biostar known for their great OEM style Boards and Asrock for their quality and budget boards that carries several features that of a higher end board. i would do Biostar if it was absolute tho on these two Motherboards i know the Card placement is restrictive on the airflow for the cards in CFX or SLI but that can be remedied usually with a small thing to seperate them alittle bit more. but the Analog system Biostar uses on the power phases seems to do the trick. a reviewer was able to go as high as 4.8ghz on a 8 Core Bulldozer without issue i might add.
the Asrock would be a alright option if Overclocking isn't a function needed by the user but style is as it's all black and gold can give a case like the CM 912 or others like that a good pop of looks, it does got better spacing for CFX and SLI to breath which helps alot. Asrock was part of Asus and they kept the quality as they left Asus and managed to give great mobo selection for the right kind of money. performance is around that of the Biostar which is pretty good so it's very small margain, the Asrocks Heatsink isn't to big and shouldn't come really close to contacting the video card unless it has a backplate then it gets close but it's not like the Biostar where if a backplate is on the card it comes close to touching.
Trinity will not be AM3+, PileDriver is AM3+
16x / x4 SLI/CFX isn't much different from 8x / 8x very small in gaming, it's only noticed if your a benchmarker which givin how your a decent overclocker and that Overclocking isn't a neccessity your not a benchmarker. other then that 16x / x4 can provide sufficient Video Card power to games in dual Card situations
as for Gigabyte i own a 990XA-UD3 which is 10 bucks more and it's one hell of a Mobo from my experience. i've looked at the 970 Giga and Asrock and they look alright for a avg user i would get the Giga tho if the Biostar cannot be had also to there's another reason i choose Biostar is cause of the Warranty the Asrock is 1 year Biostar is 3 years
i don't know if any of it make sense as it's 4am and i been up for over 24 hours....yay me..