I have purchased two graphic cards for my rig both being a GTX970, but one is a gigabyte g1 4gb while the other is a msi 4gb oc!
Will they both work in sli?
Yes, you can SLI/Crossfire the same GPU model coming from different brands. There's only one detail you have to keep in mind; if their working frequencies or their VRAM amounts are different, they'll both clock/size down to the slower/smaller of the two.
You can overclock the slower one to match up the faster one when it comes to frequencies, albeit the same can't be said for VRAM.
They will work, take a look around the internet to find CPU/GPU timing for SLI optimization to maximize gains, but they work fine without any extra work.
Yes, you can SLI/Crossfire the same GPU model coming from different brands. There's only one detail you have to keep in mind; if their working frequencies or their VRAM amounts are different, they'll both clock/size down to the slower/smaller of the two.
You can overclock the slower one to match up the faster one when it comes to frequencies, albeit the same can't be said for VRAM.