Benefit of more ram with respect to processor speed?

[Daniel]

I work in a computer store and earlier today I got a in a bit of an argument with one of the sales guys. His philosophy is to sell more ram to everybody he can, where as I only sell upgrades to those who actually need it (most of our customers aren't extremely wealthy, otherwise I would).
I generally follow a simple rule. If you're not a performance user, e.g. when I ask them what they use the computer for they say "you know, internet, facebook-ing, and email," I don't try to up-sell if they have at least 2gb on 7 or 1gb on xp.

This got me to thinking however, is there a threshold for ram benefit with respect to processor speed. If you're running a P3 on 6GB of ram (very unlikely if not impossible) then how much of that ram are you actually using (again assuming your on x64).
It seems that by the time the processor is able to retrieve X amount from the RAM, perform the calculation and then return the data to the RAM that the data could have been loaded from the HDD to the memory (since modern architecture supports non-processor intensive loading).

To further simplify / explain things, if you have a P4 and an intel i7 (separate machines) and you benchmark them both with 1gb, add another 5gb to bring them both to 6GB and then re-benchmark, which will see the greatest increase in performance?

Thoughts?
(I'm comp sci, not comp engineering, so I don't know that much about hardware).
DrDave: You must have missed the part where I said I work in a lower income area computer store. Again, not the most educated crowd (generally). So yes, I understand these applications. However most of them are toolbars or other minor items that do not consume more than ~3MB. Even with 50 of these running you're still only at 150, which out of 2GB isn't a lot.

My question isn't concerning the *general* user. It is a applied engineering question. For future commends, please consider both benchmarks to be performed on clean installs of win7 x64.

[DrDave]

I guess you aren't aware of the fact that 80% of the general public hasn't a clue how to even run a PC and generally loads it up with a bunch of worthless trinkets and baubles that uselessly run in the background eating up resources. My money is on the ram. It's also plain to see you have about as much experience and education in computer science as a water buffalo considering you even have to ask such a question.
Edit: You are trying to say using virtual ram would be a better path? That's absurd. Ideally, your PC shouldn't use ANY virtual ram period. What do you suppose happens when the processor ends up shuffling more data to and from the hard drive than it does processing the original programs?

[Ash]

More ram doesn't make any difference to processing speed. The only way ram will slow down your computer is when you run out of it and your computer starts using virtual memory. But it's very obvious when it happens because your computer will have error messages pop up and it will slow to a snails pace.

It doesn't matter if you have 2gb or 16gb of ram. It will be the same. You can, however, slightly increase the amount of cycles per second by using ram with a higher clock rate, but it really makes very little difference.

[m6502]

RAM and processor speed accomplish different things. You need enough RAM to hold all your data in memory so it isn't swapping to disk. How much that should be depends on your applications, not what speed the processor is. Having too much RAM doesn't hurt, but it doesn't help either.
Disks are orders of magnitude slower than RAM, no disk can keep up with a processor, even the RAM can't do that in many cases. Good coding tries to keep data in local CPU registers to avoid the latency of accessing RAM, let alone a disk.

Intel's best P2 chipset (the 440GX) supported 2GB of memory, and some systems used glue logic to expand that limit further. ServerWorks chipsets on the P3 supported at least 4GB, some might have gone further, I'm not sure. It was possible to exceed 4GB in those days using PAE. But certainly nothing with that much RAM in the consumer sector though.
Some applications benefit from that much RAM - database servers for example. A more consumerish example would be raw uncompressed video capture. The most reliable, lossless raw video capture system I've had was an old P2 machine with plenty of RAM and monster I/O, most people probably wouldn't believe it unless they saw it in action.

But I agree that for most daily apps, you don't need a huge amount of RAM, and in my opinion it's the easiest thing in the world to upgrade later, at a cheaper price than what it costs today. One of the most important specs on any system, in my opinion, is the maximum RAM capacity (not how much is installed). This is one of the most under-reported specs and frequently the item that limits the machine's useful life. However, I don't think you have to worry about loading it up with RAM from day 1, it's easy to add it later - as long as it has room to expand. I guess many people won't know enough to realize *when* they need more RAM, though.

I wouldn't draw a relationship between CPU speed and optimal RAM size - the RAM you need depends on applications, that's all. The reason newer systems need more RAM is because they use larger/more bloated operating systems and software, not because the CPU is faster.