All is not rosy in the land of multi-monitor MacBook Pros. As I mentioned there, I’m driving two large external monitors through USB, using Diamond adapters to connect USB to DVI; the USB plugs run into a Belkin USB hub, which runs into a single USB port on the side of the MacBook Pro with which my employer generously supplied me. (I will give you guys an iPhone app very soon; promise.) The dream is then that I can then run a bunch of other USB devices off the hub as well: iPhone, mouse, camera, etc.
It sadly hasn’t worked out that well, for reasons that illustrious Stevereads commentator mrz explained in comments to that post:
1. There’s just not enough bandwidth in USB — much less in a USB hub, which has to split one USB port’s worth of bandwidth across seven devices — to power a high-resolution monitor (much less two high-resolution monitors). My monitors would periodically slow to a crawl, and would slowly repaint the screen from top to bottom. I had to unplug the USB hub at this point, so that OS X could shift everything onto the built-in monitor; once it did that, the speed returned to where it should have been.
2. The USB hub — possibly because of item 1 — has died. None of the components plugged into it work, individually or together. When I unplug any of them — say, the mouse or a monitor — and plug them directly into the MacBook Pro, they return to life.
I can live with item 1: sure, I move windows around, and the rendering doesn’t really keep up with the movement, but it’s better by far to have two slow monitors than only a built-in MacBook Pro screen. Obviously I can’t live with item 2: I can’t stand to have a hub die after only a few days of use.
I tried to call Belkin support, but it’s another Indian call center. I find few things more disheartening than finding Indian tech support on the other end of the call; it speaks of a tech company that wants to save money (hmm: flimsy, cheap product?) and doesn’t care at all about helping its customers.
I may try to find another, better, more reliable USB hub, but the Belkin one gets fine reviews on Amazon. I’ll have to look around more closely.
The manufacturer almost doesn’t matter for USB hubs. They almost all use the same hub chipset, which sucks. My recommendation is to get smaller hubs that are designed to run powered or unpowered and then run them unpowered. This usually means you can’t plug in more than one or two devices that aren’t powered themselves but the non-poweredness seems to extend the life of the hubs almost indefinitely. It seems like the USB hub chipset everybody uses doesn’t have the proper mechanisms in place to dump excess current when powered, and so they dump it as heat and the chip eventually fails. Planned obsolescence? I don’t know. You could try hacking a new hub by opening the fucker up and putting a heat sink on it…that might help, but I’ll bet if the designers were too dumb to fix that, they’re too dumb to get other problems correct. So really, just avoid hubs if you can. They suck.
If you have a macbook pro then it has an ExpressCard slot. Just get a mac-compatible USB ExpressCard. I’ve seen ones that have four ports. You could probably comfortably hang the USB video adapters off of that and a couple of other devices. Then, just plug in any remaining devices into the on-board ports. Ta-da!
What would probably be even better would be an express-bus video card but those don’t seem to exist. The closest thing would be an express-bus to PCIe-card-cage adapter that you put a PCIe video card in. Those also seem hard to come by/expensive. After that is the new generation of ExpressCard laptop “docks”. These include a host of ports, though the ones I’ve seen don’t seem to have dual DVI. They tend to have a single DVI and single VGA, and I’ll bet that it’s one or the other and not both at the same time. Though, these things tend to clock in at $150-$200+.
So I think you’re probably best off with a 4 port USB ExpressCard, especially considering you have the working USB to video cards anyway. It’s cheap, and it will have the highest probability of success.
I have a variation on this problem. My second video adapter is a PC Card, and the rendering is just not fast enough. I have been considering getting a USB card instead but wondering if it would fix the rendering speed problem. I have plenty of USB ports, so I wouldn’t need to use a hub.
I’m sorry I can’t help with the main problem, but I have a response to this:
I’ve found many of the Indian tech support people to be quite good. Naturally tech support varies wildly in quality; there was some pretty awful homegrown American support back before the current trend, too. It all depends how familiar they are with their products…