I upped the memory on both XP x86 & x64 systems to 2GByte per core, both
C2Quads.

In my i7-2600 + 2 EAH5870 GPUs, I had 8GByte DDR3 1600MHz.
I tried 32Gbyte, which doesn't work a.t.m.(?*), but 16GByte is working
OK and makes the whole system a lot more responsive.
In WIN 7 (i7-2600), it has the biggest impact.
Ofcoarse, this a 64bit WIN7 and also using HT, so 2GByte per thread.

*(Maybe a BIOS update, although the INTEL DP67BG mobo can handle 32GByte)
Anyone who has some experience whith the amount of DRAM and BOINC?

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As long as the system has sufficient memory for everything you are doing there shouldn't be any issues. In our test lab I determined that 2GB for 32-bit systems and 4 GB for 64-bit systems was a more realistic minimums than Microsoft specifies. Each CPU instance of the S@H app doesn't take very much to run. I think on my server where I run 24 at once it does use around 1GB for all 24 threads. That just has to do with the volume of tasks I'm running.

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SETI@home classic workunits: 93,865 CPU time: 863,447 hours
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As long as the system has sufficient memory for everything you are doing there shouldn't be any issues. In our test lab I determined that 2GB for 32-bit systems and 4 GB for 64-bit systems was a more realistic minimums than Microsoft specifies. Each CPU instance of the S@H app doesn't take very much to run. I think on my server where I run 24 at once it does use around 1GB for all 24 threads. That just has to do with the volume of tasks I'm running.

Well WIN XP or the SERVER version, doesn't need more then 1Gig per core, maybe
even less.
WIN7 needs a bit more, or handles memory better/more efficient, using the
same machine to browse the web, handle e-mail, while running BOINC,
more memory, RAM, improves responce and speed.

But, that wasn't the question :-).

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As long as the system has sufficient memory for everything you are doing there shouldn't be any issues. In our test lab I determined that 2GB for 32-bit systems and 4 GB for 64-bit systems was a more realistic minimums than Microsoft specifies. Each CPU instance of the S@H app doesn't take very much to run. I think on my server where I run 24 at once it does use around 1GB for all 24 threads. That just has to do with the volume of tasks I'm running.

Well WIN XP or the SERVER version, doesn't need more then 1Gig per core, maybe
even less.
WIN7 needs a bit more, or handles memory better/more efficient, using the
same machine to browse the web, handle e-mail, while running BOINC,
more memory, RAM, improves responce and speed.

But, that wasn't the question :-).

Perhaps you could clarify your question.

It seems like you are asking for a RAM to CPU(core/thread) ratio that is optimal. Which doesn't really exist. The optimal amount of RAM, for the system, depends on what activities the system is doing.

As an example. I have 4 core systems that are crunching away at S@H & doing all of their required server duties with only 2GB of RAM. While others have 2 cores and have 6GB of RAM. As the ones with 6GB need more memory for the functions they are doing.

On my home theater PC I was running 8 threads of S@H, several other apps, & watching HD movies with 4GB. Which is sufficient for that system doing all of that.

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SETI@home classic workunits: 93,865 CPU time: 863,447 hours
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As long as the system has sufficient memory for everything you are doing there shouldn't be any issues. In our test lab I determined that 2GB for 32-bit systems and 4 GB for 64-bit systems was a more realistic minimums than Microsoft specifies. Each CPU instance of the S@H app doesn't take very much to run. I think on my server where I run 24 at once it does use around 1GB for all 24 threads. That just has to do with the volume of tasks I'm running.

Well WIN XP or the SERVER version, doesn't need more then 1Gig per core, maybe
even less.
WIN7 needs a bit more, or handles memory better/more efficient, using the
same machine to browse the web, handle e-mail, while running BOINC,
more memory, RAM, improves responce and speed.

But, that wasn't the question :-).

Perhaps you could clarify your question.

It seems like you are asking for a RAM to CPU(core/thread) ratio that is optimal. Which doesn't really exist. The optimal amount of RAM, for the system, depends on what activities the system is doing.

As an example. I have 4 core systems that are crunching away at S@H & doing all of their required server duties with only 2GB of RAM. While others have 2 cores and have 6GB of RAM. As the ones with 6GB need more memory for the functions they are doing.

On my home theater PC I was running 8 threads of S@H, several other apps, & watching HD movies with 4GB. Which is sufficient for that system doing all of that.

My original question was, running BOINC and the optimal amount of memory
needed.

But there is a (big) difference between XP64 and WIN7 x64.

Another difference, running 4 different projects on a C2Q using XP64, also
projects with and whithout GPU, or GPU only and CPU only.

CPDN WU need 1 gig per core, so in this situation 1 Gig per core is needed.
But I realize this isn't about memory only, combined CPU & GPU projects
on 1 QUAD system, stresses the whole system, not only memory, so it gets
to complecated to just pin it down to memory.
And more or less answered my own original question.....

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It seems like you are asking for a RAM to CPU(core/thread) ratio that is optimal. Which doesn't really exist. The optimal amount of RAM, for the system, depends on what activities the system is doing.

Yes. And an easy way to find out, if you have "optimal" amount of RAM installed is to turn off the pagefile. If the machine is still doing everything it should without complaining about not enough swapspace, than you have at least the "minimum optimal" amount, where the OS does not need to move things front and back between RAM and hard drive. Of course it has also some small positive effects on the performance if you have still few GB free (with disabled pagefile), so the caching functionality of the OS can use that. But getting rid of the pagefile had for me always the most noticeable effects on performance, so that's how I define the optimal amount of RAM and that's the amount I try to have installed in my machines. All my three active systems are running currently without a pagefile.

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It seems like you are asking for a RAM to CPU(core/thread) ratio that is optimal. Which doesn't really exist. The optimal amount of RAM, for the system, depends on what activities the system is doing.

Yes. And an easy way to find out, if you have "optimal" amount of RAM installed is to turn off the pagefile. If the machine is still doing everything it should without complaining about not enough swapspace, than you have at least the "minimum optimal" amount, where the OS does not need to move things front and back between RAM and hard drive. Of course it has also some small positive effects on the performance if you have still few GB free (with disabled pagefile), so the caching functionality of the OS can use that. But getting rid of the pagefile had for me always the most noticeable effects on performance, so that's how I define the optimal amount of RAM and that's the amount I try to have installed in my machines. All my three active systems are running currently without a pagefile.

Switching off PageFile is indeed a good check and I tried it out running
only BOINC.
HDDs are a bottleneck, quite noticeble when f.i. only 1GByte(total)
is installed.

Windows XP (64bit)needs less RAM, compaired to WIN 7 (64bit), when running BOINC whithout a pagefile. With 16GByte on an i7-2600 it's using about 16%
running BOINC, 8 threads(MB WUs) and 2 on each (ATI 5870)GPU.

Even room for browsing the WEB, checking on e-mail and copy and paste text
or a screendump.
Normal amount of system processes running.

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Even room for browsing the WEB, checking on e-mail and copy and paste text
or a screendump.
Normal amount of system processes running.

I have 4GB in my Win7 x64 system (dualcore), with 2xMB on CPU + 1x Collatz or 2x Milkyway on GPU and few programs I usually use I don't have more than 2GB in use (now for example just 1,76GB with 60 processes running), the only time I was over 3GB was when I was out of Seti WUs and was running 2x Rosetta on the CPU.

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Even room for browsing the WEB, checking on e-mail and copy and paste text
or a screendump.
Normal amount of system processes running.

I have 4GB in my Win7 x64 system (dualcore), with 2xMB on CPU + 1x Collatz or 2x Milkyway on GPU and few programs I usually use I don't have more than 2GB in use (now for example just 1,76GB with 60 processes running), the only time I was over 3GB was when I was out of Seti WUs and was running 2x Rosetta on the CPU.

Rosetta is also known for it's high(er) memory use, like CPDN
So it appears, there isn't an optimal amount of RAM, maybe for a
specific OS and # of task(s).

Thanks to HAL9000 and Link, taking the time to answer and explain my (weird) question.

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So it appears, there isn't an optimal amount of RAM, maybe for a
specific OS and # of task(s).

As long as it's dedicated SETI-only cruncher, than yes, it's basically the OS and number of tasks, but as soon as the machine has something more to do or is running also other projects, it gets quite complex and has to be watched from time to time, specially when using new programs.

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Even room for browsing the WEB, checking on e-mail and copy and paste text
or a screendump.
Normal amount of system processes running.

I have 4GB in my Win7 x64 system (dualcore), with 2xMB on CPU + 1x Collatz or 2x Milkyway on GPU and few programs I usually use I don't have more than 2GB in use (now for example just 1,76GB with 60 processes running), the only time I was over 3GB was when I was out of Seti WUs and was running 2x Rosetta on the CPU.

Rosetta is also known for it's high(er) memory use, like CPDN
So it appears, there isn't an optimal amount of RAM, maybe for a
specific OS and # of task(s).

Thanks to HAL9000 and Link, taking the time to answer and explain my (weird) question.

You can plan for a "worse case scenario" if you want. If these CPDN takes can use 1GB each and you are could run 8 of them at once. Then 12-16GB of RAM wouldn't be out of the question. If you never use more than 3-4GB then it just becomes extra cost. Other the other side. I have never seen a computer or program complain about having to much memory.

If you work with a lot of files or a few large ones often windows will also use your memory that isn't used by apps for caching. Which it doesn't really reflect in the "used memory" like you might expect. After transferring an 8GB file form one machine to another it might say you are only using 1.5GB of memory, but it has otherwise consumed all of it.
Windows 7 will show you this in Task Manager on the Performance tab in the lower left. Which sort of looks like this:

Physical Memory (MB)
Total		4096
Cached		1671
Available	3232
Free		1595

Once the value for "Free" gets low then a system starts to get slower as Windows is often not smart enough to release this memory correctly. There are a few tricks to try and force it to release the memory, but generally rebooting is the easiest solution.

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Once the value for "Free" gets low then a system starts to get slower as Windows is often not smart enough to release this memory correctly. There are a few tricks to try and force it to release the memory, but generally rebooting is the easiest solution.

From my understanding, what you have to worry about is the Available memory getting low, it is normal (and should actually improve performance) to have low Free memory as that suggests superfetch is doing its job and caching frequently used programs and files to your unused memory. Mapped files are going to have a low priority and shouldn't interfere at all with active processes.

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I decided this post was much more of a question about ram than an answer so removed it to a new thread.