Everyone who's running an SMP client should check to see if they've got the upgraded version of the FahCore_a2.exe core file. It's speeding up the calculations on 2662 WU's by over 35% on my Opteron, and makes the client utilize the CPU more efficiently. It appears that even machines with several cores will be able to run this core efficiently enough to make it useful to employ all cores in a single client. Since most of us are using VMWare Virtual Machines to run the Linux SMP client, that may not be possible. It will still increase output no matter how many cores you use. I don't know why the Windows SMP clients can't benefit from this update, but since this core isn't available for it yet it may well be worth moving to a VM running the Linux SMP client just for the output gain.
Warning: Do not upgrade in the middle of a WU unless it's running a different core, because it will trash the current WU if you do. So if you're running a Project 2619 or a Project 2662, let it complete before upgrading the core.
Here's how you can tell the core it's presently running. When it first starts crunching the WU, it says something like this:
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[23:30:41] Folding@Home Gromacs SMP Core
[23:30:41] Version 1.91 (2007)
[23:30:41] Preparing to commence simulation
That was the older core. There's a problem with the system updating authomatically like it should. Here's what they say at the FoldingForum about it:
FoldingForum OP wrote:We've released a new A2 SMP core to advanced methods (currently projects 2619, 2662) for OSX and Linux.
This core is much more efficient in terms of its CPU utilization than the A1 core or the first-generation A2 core, and we're excited about the greater scientific productivity it allows.
The new core version is 2.00 (2.01 for OSX); if you don't have a previous A2 core it should auto-download. If you have an A2 core prior to 1.95, please delete it. Those cores do not always download upgrades automatically and will run much slower than the new version.
Edit by Mod: Based on comments below, if your current WU is using FahCore_A2, updating will probably destroy it, so wait until it finishes.
Here's how the new core looks when it starts up:
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[15:33:14] Folding@Home Gromacs SMP Core
[15:33:14] Version 2.00 (Wed Jul 9 13:11:25 PDT 2008)
[15:33:14] Preparing to commence simulation
On the completion of your next Linux (or Mac OS X) SMP WU, shut down the client, delete FahCore_a2.exe and restart the SMP client. I went from nearly 28 minutes / frame on a 2662 to < 18 minutes / frame by this change, which forces a new FahCore_a2.exe to download. I went from ~900 PPD on those 2662's to over 1500 PPD, which is even higher than 2605 WU's! Here's the FoldingForum.org thread about it: new A2 core released--on advanced methods but I can't seem to find the one I read earlier, because I think the one I read was more helpful and had Dr. Pande mentioning various useful bits of information.
Anyway, UPGRADE AS SOON AS YOU CAN! It's WORTH THE EFFORT.
They say here that:
We haven't updated A1--this is just an update to A2. They are used by a different set of projects. A2 gives us a number of benefits, both scaling-wise and science-wise. As the new core settles in, we'll be offering more A2 projects and fewer A1. But that's the medium-term plan.
So the sooner we all get updated the better our production will be, and the fewer problems we'll have as a team.
Edit: There's mention of the new a2 core in notfred's Diskless Folding Virtual Appliance thread after the core's July introduction, by the way, and maybe elsewhere, but I only noticed this thing yesterday.