Regarding Gigabyte and Asus GPU RMA

Hi

i have two concerns -

1. Can anyone confirm that how long does Gigabyte take to RMA it's graphics cards? Also, do they require an invoice for it or just the serial number will do? I have a Gigabyte GTX 660 which is showing artifacts in all games so I think it's gone bad now. Still has warranty till June, based on the box. Please let me know..

Thanks

2. Also, can I claim warranty for an ASUS GPU based on serial number?

Someone please reply as this is urgent.

Thanks!