Life as a Physicist

I’ve recently become a huge fan of VirtualBox. This is virtual machine software – it allows me to run one operating system (like Linux) inside another (like my Windows box). I’ve tried two others – Virtual PC from Microsoft and VMWare. The nice thing is these are all free. This type of software is pretty cool – it lets you run a machine within another machine. I use these all the time – mostly to run Linux because I need it for work.

Virtual PC was my old mainstay, however its Linux support is barely functional (it doesn’t support a very good graphics card and so default installs of Linux often fail). VMWare took over my USB devices on my laptop and wouldn’t give them back until I rebooted. But VirtualBox seems to be quite good. And of the three it has the nicest user interface of the three in my opinion.

There is one problem with it, however. Its license. I’d not caught this until today (despite using it for several months). It is free for anyone to evaluate. And if you are using it at home for private development work then you are safe. If you are in an educational institution you are ok. This covers my use of VirtualBox for my research. But what if you are at a National Lab – like Fermilab or CERN? As far as I can tell, you have to pay. This is too bad as a substantial group of people who would want to use this in research are at these national labs. I guess they are stuck with VMWare or Parallels (do people pay for this? Or is it free?).

UPDATE: As Jeff points out in the comments, the licensing FAQ makes it clear that folks at CERN/Fermilab can use VitualBox without problems… the problem only comes in if centralized CERN mgmt tries to install it on everyone’s PC. Very nice!

I like building my own computers. I’ve been doing it for years. There is something very satisfying about putting together a computer who has its components “lovingly” chosen, seeing it boot. And then playing with the low level parameters to try to get every last bit of performance out of it.

I gave up about three years ago – it takes too much time. If you buy from Dell or HP then you know that all the bits will work together well – that they have supplied (hopefully) debugged drivers. If you build it yourself you have to find the proper drivers. Sometimes there is a funny interaction between two components and the system isn’t stable – though individually each works just fine. This can cost hours. And if something breaks down the line – well, there is no warrantee on the whole system so you are left spending time debugging. The downside of purchasing from Dell or HP is that you get the cheapest possible components. And the system has decent performance, but it won’t be great.

Intel has released a new and very cool CPU – the Core i7. The base chip is 4 CPU’s, and it is so new that it is quite expensive: 300 bucks for the the cheap version of the chip. But it is fast. About 20% better for the same clock speed (wow!). And it has four cores. And they have re-introduced hyperthreading. And it has simply awesome inter-core bandwidth (check out this ars-technica article for details). And it does the same job for less power as well. In case you think I’m off the wall, here is an outtake from the ars’ article:

When I set out to write this article, I had three areas I wanted to explore: HT performance, performance scaling in Nehalem vs. the QX9650, and the performance difference, if any, between 32-bit and 64-bit mode. Having done so, I could almost write the shortest conclusion on record: Nehalem is great, Hyper-Threading = generally awesome, and 64-bit > 32-bit mode.

I decided it was time to reward myself for making it through teaching last quarter. Check out the bottom of the cpu:

More pictures are available in the usual spot should you want to check out some geek pr0n (J-mo even managed to make an appearance).

The builds these days aren’t as fun as they used to be: everything is keyed (for example, notice the half-moon notches in the CPU). It is almost impossible to insert anything the wrong way. Or if you buy the wrong component it just won’t fit. The power supply cables are keyed as well – so you can’t actually put the 12V CPU supply into the PCI-E socket on your high power video card.

But that doesn’t mean that it didn’t provide me with some entertainment. After I first assembled it and powered it up it did something I’ve never seen any system do. The mother board powered up, fans spun up, and then about 4 seconds later everything shut down. About 5 seconds later the process repeated itself. It would keep doing that until I pulled the plug out of the wall. I swapped everything! Nothing worked. So I finally decided it was the CPU – that was the only thing I couldn’t replace locally for a test. At the time no one really knew what was going on either. So I sent it back. It was going to take a week before a new CPU was returned.

And during that week comments started to arrive at newegg. The memory isn’t compatible! I had three sticks of memory and I didn’t think all three could be bad – so I didn’t think to try something new. Sure enough, when the new CPU arrived it failed exactly the same way. A quick trip to Fry’s to get some cheap memory – and up the machine comes! Ah, the price of the bleeding edge. This system is expensive enough (just a hair under 1000 bucks) that few people are building it right now.

But as of this last Friday it is running, with 64 bit Windows 7 powering it. Of course, on Saturday I got on a plane to come to Switzerland for a workshop so I can’t really play with it. I came “this close” to canceling my trip. No over clocking yet – and I’d like to also figure out how to measure its power usage – tweaking now isn’t only about performance, after all.

If you have the time to do a custom build – I definitely recommend it. To help you out in situations like this it is key to find a store (like Fry’s and Newegg) that have liberal return policies incase you accidentally buy incompatible memory.

P.S. How do you know when you paid too much for a power supply? When it comes in a felt bag!!!