Bilibom,
I'm a lurker here and read more to learn than anything else, but I have to say these guys have been immensely patient and, no offense, but getting information about your system has been like pulling teeth. Looks like you've just recently joined, presumable to ask this question, so since your new we'll take a deep breath, unload all the defensive feelings and let's review some things here.
1. This is a free board and kindness/graciousness is valuable currency.
2. These guys are the experts, we are the needy; if they ask for specific info, there's a reason. If we can't fathom the reason, consider that maybe that's why we're the amateurs and they're the experts.
3. Read over your previous posts; you asked how loserOlimbs knew your RAM was running at 333MHz, yet you yourself told us in your earier postings that PCmark05 showed your RAM speed as 333MHz.
4. Just like any case in a court of law, facts mean everything. If you're experiencing a problem with a system, provide all the in-depth technical information you can find, no matter how unrelated it might appear to you: Motherboard number (all of it, not just the package name), RAM type and part number (there's more than one flavor of RAM for each type), BIOS version and manufacturer, Processor part number (not just speed), PC Company (if appicable), periphials connected (yes, they can make a difference), and anything else you can think of. In your particular case, the motherboard and BIOS type will determine how your motherboard handles RAM.
It helps to keep your system info recorded in a text file or something so that when anyone asks, you can just cut and paste and BAM, there it is. Don't worry, no one's going to be able to use it to hack into your system.
Hope that clears up why everyone keeps trying to pull information out of you...it really IS relevent. Chalk it up to misunderstanding and let's move on. If you need any terms explained, don't be afraid to ask. That's what everyone's here for, and trust me, everyone knows how intolerably frustrating computers can be.
All I can offer on your questions is, 1) Other than BIOS, which everyone's trying to help you with already, you can take your RAM down to a local computer shop and have them test your RAM and make sure it runs at the right speed, and 2) BIOS and/or motherboard jumper settings are what determine RAM speed; sometimes it's autosensed, sometimes it's manually changed....it depends on the motherboard and BIOS manufacturer. By knowing what the full motherboard part number and BIOS manufacturer/version you have, these guys should be able to help you out with that, even if the answer is "you can't".
BTW, have you tried calling your motherboard and/or RAM manufacturer and asking them? That would be one sure-fire way to investigate loserOlimb's theory on the dual channel RAM frequency. Many times you might get a suggestion from someone about something they've heard, but it's simply a pointer for you or some other reader to follow; they might not remember where they read it, but it might job someone's memory or give you something to ask your manufacturer.
From your own post, if your Motherboard sees four 1GB modules of RAM as only 3GB, sounds like something's goofy with the way your motherboard is designed and I would not be a bit surprised if it dropped buss speed with 4 pieces of RAM. Heck, I'd personally be more concerned with losing 1GB of RAM than 67MHz of RAM speed (400-333MHz).
Hope this helps,
Jeff K.