Just wanted to share my experience with fan replacements. I put some Cougar Vortex HDB fans (
http://www.newegg.com/Product/Product.aspx?Item=N82E16835553005) in my cubes, and they sure do run nice and silent but at the expense of pushing a lot less air than the stock fans. The cubes do run on high with these fans (I ran them for over a day like that) but it gets way too hot for my liking. I touched a thermometer to one of the heatsinks and it read over 90°C (ambient is ~21°C). So I put the original fans back in and they're running much cooler now.
afaik the network interface on blades and cubes is 10 MB. some network equipment may not deal with this properly. if it's a managed switch, try setting the port config to 10MB. however, a good switch should autosense to 10 MB. I do not know if they are half or full duplex.
My router reports that they are 10mbps half duplex, if that matters to anyone. I have two cubes running on a proxy on an Ubuntu machine, and system monitor shows that the bandwidth doesn't usually goes above 40 kB/s (320 kbps).
I know for a fact that they're finicky if you have android phones or tablets ect on the same network.
I think that a possible way to mitigate this if you have an old router laying around is to put your cubes on their own subnet. Plug the cubes into the LAN ports of your old router, and use the WAN port of the old router to connect to your existing network. You have to configure the router so its LAN is actually a different IP subnet - for example if your existing network is 192.168.1.X, then the cube subnet has to be something else, like 192.168.2.X.
And for good measure, here are my PSU datapoints:
Rosewill Xtreme RX750-S-B 750W: fail - overcurrent protection kicks in after a minute or so with a single cube on low
EVGA NEX750G Gold 750W: success - runs two cubes on high, though the fan is on max
EVGA 600B 600W: success - runs a single cube on high, nice and silent, but the PCIe power cables get hot
Perhaps dogie would be interested in keeping a table in the OP about which PSUs have been reported working / not working, and how many cubes the PSU can power?