Yes, the metal base gets VERY hot on the v2's as well. I use a thermaltake usb fan for the underside and it keeps it much cooler
Just picked up the two v2 units I have in front of my laptop that have been running all day. The bottom plate is cool enough to hold each in my hand comfortably. Running these at default specs and they consistently do 56gh+. BTW, anyone have ideas about stacking the v2 units as I've seen done with Gridseeds? Thought about using standoffs but doesn't seem like they would be stable. I've done a little experimenting and it looks like about 1½" spacing between gives enough room for proper cooling.
What is it about these units that causes such drastic end user experiences? Of the 3 I have, all 3 are almost too hot too touch on the bottom when running. Default specs I never see more than 40GH. Did you have any problems getting them both to run at the same time?
Running 2 at a time seems to work OK. Sometimes CGMiner will switch one or both units to a new AU3 number, but they keep on mining. Here's my setup:
1} Dell M4500 64-bit i7 Quad, 16gb, stand-alone DSL connection. CGMner runs OK, but with other mining hardware BFGMiner x64-seems to run faster and more stable. Looking forward to trying the v2's with BFG 5.20 when it becomes available.
2} Have used these Anker/Orico/Aitech 10-port aluminum hubs for 2 years with no problems. Having a power switch makes it easy to reset without unplugging the U3's When a unit goes zombie, just shut down CGMiner, power off the hub, wait a few seconds, restart the hub and restart CGMiner.
http://www.amazon.com/Aitech-Adapter-backward-Compatible-aluminum/dp/B009NESU4M/ref=sr_1_1?ie=UTF8&qid=1429186867&sr=8-1&keywords=aitech+10+port+usb+3.0+hub3) Use this Supernight power supply to run both the V2 units and the hub. Meanwell brand seems to be the same unit. Some of these don't come with a thermal switch that cycles the fan, so I install one. It cuts down on the fan failures which is a problem with these; I have to replace the fan every six nonths or so. Anyone know of a quality ball-bearing replacement fan that will fit? The stock PS units that come with the v2's are not very stable and get too hot with normal use.
http://www.amazon.com/SUPERNIGHT-Universal-Regulated-Switching-Computer/dp/B009EIANT2/ref=sr_1_4?ie=UTF8&qid=1429186484&sr=8-4&keywords=12v+30a+power+supplyWill be trying 4 more U3's on another similar machine when I get things set up. Will post here how it goes.
Update as promised on running 4 v2 U3 units at once. Machine and setup are as above; running four U3's in the Anker hub, same PS. In a 24-hour period it's common to get at least 1 unit to go zombie. Reset is easy with the Anker hub; no unplug-plugin hassles. One unit seems to slow down to mid-40's GHS from an itnitial 56+. Will crack this one open and check the paste.
A note on the startup sequence of the Anker/Orico/Antec 10-port aluminum hub. Counting 1-to-10 from the plug end of the hub, these have a strange sequence loading ports when turned on. It goes 6-5-10-9-8-7-4-3-1-2. Plugging in the U3's in that order seems to help a lot with stable running.
Have been experimenting with stacking the units and will post some ideas as they are tested. Also plan on using a larger PS to run up to 10 units from one hub in the future. Wish LukeJr would hurry up and post BFGMiner 5.2 as I think the U3's would be quicker and more stable running under a 64-bit program.