[citation][nom]Junoh315[/nom]The reason why I think that the 7990 shouldn't be labeled is due to the fact that Newegg and some other sites don't carry it. If Powercolor is the only person making it, stay far away. There is a custom 7970 that's essentially the same thing but it takes up 3 slots due to the large video card. You're better off buying two 7970s, although that would still be overkill for anything that you'd need nowadays. One 7970 or GTX 670 is all that anyone needs(two in SLI or Crossfire if you want multiple displays). AMD cards have a lot of issues still, one example being micro-stuttering*, which don't usually occur in Nvidia cards. They may have raw power but their designs are typically flawed and their driver updates don't really improve much when compared to Nvidia. They're good for under $100 video cards. The Sapphire 6670 that I put in my Mom's PC does really good at what it's supposed to do, play Sims 3 on the highest settings while using as little wattage as possible (max watts is 72, I don't plan on over-clocking it due to power issues). However, it doesn't add the textures instantly when you speed up time. That might be a RAM issue though, I'll be able to find out after I get her 8 GB of RAM for Christmas. If you have a PSU with only 300 Watts then I would suggest no other card.*In tests performed in Battlefield 3, a configuration with two GeForce GTX 680 in SLi-mode showed a 7% variation in frame delays, compared to 5% for a single GTX 680, indicating virtually no micro stuttering at all. A configuration with two Radeon HD 7970 in CrossFireX-mode, on the other hand, showed an 85% variation in frame delays, compared to 7% for a single card, indicating large amounts of micro stuttering. Having more than two Nvidia cores or one AMD core leaves you open for a large amount of micro-stuttering. "With Alternate frame rendering (AFR), the first GPU calculates the first frame while the other calculates the second one and so on. Upcoming graphics driver could provide the necessary balancing." This means that the problem will be fixed eventually but right now, it's not a good idea to Crossfire anything or SLI with 3 cards.[/citation]
Nvidia has almost as many stuttering issues as AMD and Tom's recent Cryis 3 tests are a good example of that.
Micro-stuttering is an issue that is only present with multi-GPU setups and with RadeonPro, AMD beats Nvidia in it. Even without it, micro-stutter is not a common issue anymore anyway it you use high-end modern GPUs.
AMD's driver updates improve much more than Nvidia's. That's how AMD started off this generation well below Nvidia, yet managed to get to the top. Nvidia generally starts off better, so that AMD needs to improve more is obvious and looking at driver releases makes it obvious that AMD has improved more.
The Radeon 6670 is an extremely low end card. To expect much from it seems ridiculous. The Radeon 7750 has a huge performance advantage and uses considerably less power. The same is true for Nvidia's GT 640 GDDR5 and IIRC, the GTX 650 too. That gives good reason to not recommend the 6670 unless budget is extremely tight to the point where $90-100 cards are not viable options.
Furthermore, it is a well-known and proven fact that triple GPU solutions have far less stutter issues than dual-GPU solutions in most situations, especially with modern hardware. I can even thoroughly explain and demonstrate the theories about why this happens without looking them up.
Also, at least when I look, Newegg and many sites do have one or more 7990/7970X2 cards. I do not recommend buying them, but I see them around. Powercolor is not the only company making them; there are several others such as Asus.