I have two of the old style blades. one has been chugging along nicely at 10 Gh/s with the low clock. today i started the second one. They are both sharing a 490 watt supply. the second one came up with a bunch of Xs. powering on and off got it down to 4 Xs it was running at about 4Gh/s and after the last restart is running at 1Gh/s. is this a power supply issue? do i need to give each it's own Power supply? Both are using the same Slush proxy with unique workers. 
Depends on the PSU! Its now how many Watts in total the PSU delivers, its about the Amperes on 12V it can provide! How many Amps does does your PSU deliver on the 12V rail(s)?! Each Blade pulls about 10A at 12V, so if the PSU only delivers 15A at 12V there is a problem if you try to run 2 Blades on that 12V rail! Can you post a picture of the that sticker on your PSU?
For example, one of my PSUs has 560W in total, but only 348W at 12V which is sufficient to run 2 V2 blades (2x 120W). Connecting a 3rd would 'cause the PSU to overheat and shutdown!
You might look as well for a 12V DC LED-driver with about 250-300W to run your 2 blades, those LED-drivers are much cheaper than a PSU for your desktop!