Just got this message from the server after I clicked update for the BURP project:
14/1/14 22:29:40 | BURP | Message from server: Blender needs 12122.00 MB RAM but only 3889.46 MB is available for use.

Any ideas?

Well, I'd say you don't have enough RAM for the session being rendered.

If there's work from another session that has a lower RAM requirement, you'll get that; if you get this message, the only work available is from the one that requires 12 GB.

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Click here to see My Detailed BOINC Stats

Well, I'd say you don't have enough RAM for the session being rendered.

If there's work from another session that has a lower RAM requirement, you'll get that; if you get this message, the only work available is from the one that requires 12 GB.

No session has ever required anything near 12GB of RAM. The display on the website is completely inaccurate when it comes to projects. The most I've ever seen a session take is 200-300MB and those were displayed on the website as 2-3GB, as if an extra zero is added.

Looking at the session now (1914), no one has returned results.

The memory requirements are the absolute MAX that a particular session is allowed to directly or indirectly allocate without being forcibly cancelled by BOINC - also known as a peak memory working set. During most of the rendering phase the session will be using considerably less.
It is mostly a guesstimate based on the amount of memory allocated by the Blender editor during checks, the guess made by the uploader, the phases of the moon and then an extra 20%.
The hope is to always error on the side of too much memory, since going too low will make the session fail. Additionally BOINC has some issues regarding how it treats multiple workunits and their memory requirements.

Lastly, this is used as a way to segment the farm into high- and low-mem machines from time to time to run tests. In this particular example which relates to the experimental cycles-based session 1914, multiple high-mem machines were asked to render each workunit to provide testbed data for an upcoming cycles validator.

It just seems extremely over estimated. Do you have memory statistics of how much these units actually used? I'd be surprised if it was more than 1GB.

It is around 3.7GB with some short peaks to much higher values.

Same again with project 1919
During the approval process it listed 38XX MB RAM
Now it lists 11GB...

During the approval process, the administrator takes a look at the file to see if the memory requirements (set by the user) are acceptable. You will often see the memory change after it is accepted.

I'm currently rendering project 1919 and have 10GB+ in use. My machine has also locked up twice. Could be my memory flaking out, or my kernel, or possibly blender(?). I don't get anything in the system logs. It just freezes up (mouse, keyboard, and all). I realize it's nearly impossible to track down. Just wondering if anyone else has had any problems.