Sapphire 280x vapor-x or MSI R9 290 TWIN FROZR IV

[Len]

Just wondering if anyone can help me with which card is best to buy in terms of khash/watts (after OC and undervolt) and if either aren't voltage unlocked, (model numbers to look out for).  Or even similar cards I haven't mentioned.  Ignoring initial cost.  
I will be running 4 or 5 of each, my other rig is running 7950s so I don't know much about the r9 series.
Thanks in advance! I will give a little tip to the most helpful person.

[crazyates]

I'm a big fan of the 280x over the 290. Seems to be more consistent, and undervolting is a lot easier. There are multiple ways to undervolt a 280x, VBE7 being my favorite.

A 290 will get you better hashrate, but the 280x are usually better in terms of khs/USD, as well as khs/Watt. Makes perfect sense to me.

[Equate]

280x are best in terms of money and KH/s.

[Len]

I'm a big fan of the 280x over the 290. Seems to be more consistent, and undervolting is a lot easier. There are multiple ways to undervolt a 280x, VBE7 being my favorite.

A 290 will get you better hashrate, but the 280x are usually better in terms of khs/USD, as well as khs/Watt. Makes perfect sense to me.

Thanks both of you for the help, should I go with MSI gaming 3g or Saphire Vapor-x , or are the reference models ok? any opinions?

[whoiis]

vapor x has some issues with newer bios versions and low quality components
you need to keep them comparatively cool to get decent results
https://litecointalk.org/index.php?topic=10313.0

[crazyates]

Thanks both of you for the help, should I go with MSI gaming 3g or Saphire Vapor-x , or are the reference models ok? any opinions?

I've heard some issues with the fans on the MSI cards, and the Vapor-X have some heat issues (above normal core and VRM temps).

We have the Gigabyte WF3 280x, and they're amazing. Run nice and cool, undervolt like a champ (which then run even cooler!), and are whisper quiet. Very solid.

[jameschase]

I think Vapor-x would be faster than MSI, because people compare Vapor-x to be the same as 280x TOXIC cards, and on my rig, with few days of tweaking I couldn't get more than 745 on MSI, and TOXICs run 800+ for me:

https://bitcointalk.org/index.php?topic=438191.msg4844662#msg4844662