FSB, ram speeds, support, memory controller

I'm so sorry to have this much clutter.  I understand that I've asked a lot, and I'm sorry.  The purpose of that was so I could split 500 points and have only one question for everything in the same category.

My FSB is 266.  There's a feature on my motherboard to allow me to use some sort of ratio to go to 66, 80, 100, 133, 166, 178, 200, and whatever else I left out.  By the way, I have an MSI K7N-2 Delta.  There's one 512MB stick of PC-3200 with a CL2 capability.

For fun, I tried to go with a 200MHz FSB and use CL2.  My PC didn't lock up at all.  1. So, is there some sort of other latency in this ratio thing that slows down my performance just enough to make my PC stable?  2. Am I missing the point?  3. Is my memory controller amazing, since I can do that?  4. Would you want to run at DDR400 with CL2 on your PC?

5. Is this good for overclocking?  6. Can I get an XP 3200, take up the FSB to 233, then use the ratio feature to go back down to 200MHz for the ram?

7. Is this good for ram that can only work at CL3?  8. Could I use this feature to make CL3 ram run faster (MHz) to minimize the latencies?

9. Finally, can my motherboard support PC-3700 ram?  The board will allow me to take up my ratio so that the ram can run at 233MHz, so that must mean it's all right.  10. Can I get PC-3700 ram and run it at CL2?

Thank you very much,
Radomir Jordanovic
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1) Your frequency clock is adjustable- and the slower you run an oscillator, the better it performs (generally, and only to a point). Therefore, you could run your FSB at 66mhz, and it would be very stable, but with little performance. The balance is to get the best performance without affecting stability.
2) No.
3) No. Most (good) mainboards will allow you to crank up your clock settings. It's what overclocking is all about. But they won't give you much support if you tell them your system is unstable and you boosted your FSB clock by 55%.
4) You want to use RAM that will support the fastest FSB you mainboard can. DDR400 is great, but if your maiboard only clocks up to 266Mhx, there's no point in wasting money. You won't be able to utilize that extra 133Mhz faster.
5) Yes.
6) Yes. But you would want your FSB at 266Mhz, since the board can support it. The faster the clock, the better throughput.
7&8) CL3 mode is faster. A PC100-322 DIMM can run at 10ns (100MHz) speed in CL3 mode, that is what that the 3 in PC100-322 is, and it will typically run at 12ns (83MHz) or 15ns (66MHz) in CL2 mode. A PC100-222 DIMM can run at 10ns (100MHz) speed in CL2 mode, but will typically run at 8ns (125MHz) in CL3 mode. (http://www.oempcworld.com/generic.jhtml?pid=17).
9) Yes, it will run. HOWEVER, you need to check your max FSB settings to see the maximum clock settings in your motherboard manual. PC3700 can run at 466Mhz, so you need to get your FSB that high to really see the benefit. If your mainboard maxes out at 266 mhz on your FSB, don't bother with PC3700 ram until you upgrade your mobo.

Hope this helps,
radomirthegreatAuthor Commented:
All right, then.  So, what I have is a board that supports DDR400.  I can run with a 400MHz DRAM clock at a CAS latency of 2.  As I've learned from AlbertaBeef, DDR400 that runs at CL3 is 6 billionths of a second slower than DDR266 that runs at CL2.  Therefore (and for many more reasons), I have come to figure out a lower latency allows better performance.

For 3:  I didn't mean to ask about overclocking; sorry.  I meant to ask if my memory controller is amazing because I can run at DDR400 CL2.  The reason for this question is that many ram distributors sell their CL 2, 2.5, and 3 as ram categorized by the compromizing of speed/stability.  The lower the latency, the faster the system is.  Considering that, I thought that changing the ratio of my FSB-DRAM speed would affect the DRAM by obscuring its throughput, therefore making the DDR400 CL2 ram run slower.  Is that true?

Thank you,
Radomir Jordanovic
Glen A.IT Project ManagerCommented:
1st, droswell:  His board fully supports 400MHz cpu's and 400MHz ram.  He doesn't need to upgrade it, it's brand new and based on the nForce2-Ultra400 chipset.  Also, CL3 ram is NOT faster than CL2 ram . . .  Not when it's the same frequency.  You need to do some research if that's what you believe, but I assure you that PC3200 CAS2 RAM is much faster than PC3200 CAS3 ram.

as for the questions:

1.  You shouldn't be concerned that your memory controller can run your RAM properly:  it's supposed to.  The nForce2 Ultra400 chipset lets you run your memory FSB asynchronously from your CPU FSB.  That's why you can set your memory fsb to 200MHz (for 400MHz RAM) while your cpu is set at 133MHz for 266MHz operation.

2.  No, you just might not understand the asynchronous operation.

3.  It's supposed to do that :-)

4.  Many people do.  That's the point of purchasing PC3200 LL (low-latency) RAM.

5 & 6.  Yes, your board is very good for overclocking, but don't try starting at 233MHz cpu fsb.  1st, if at all possible run your cpu fsb and memory fsb at the same speed -  that gives you the best overall performance.  in fact, you'd probably get better performance now if you lowered your memory settings to be synchronous with your CPU.   Sounds unbelievable, but you can test it with benchmarks.  There are many reviews done of mobo's that show, however, without a doubt, that asynchronous performance actually slows the PC down.  It's a limitation of the chipset.  As far as overclocking, if you buy a 3200+, start increasing your system by 1MHz (both cpu and ram, keep them the same speed for best performance, like I said) and when it no longer runs stably, reduce it back down.  That's your optimum setting.  You can increase it further by increasing voltages, but I personally don't bother.

7 & 8.  Yes, you can possibly overclock CL3 RAM with your board, but it depends on the quality of the module.

9.  Yes, you can use PC3700 RAM, but possibly not to full advantage.  Depends on your bios.  Look at the settings of your memory frequency?  What's the highest memory frequency you can run in your bios?  If it stops at 200, don't bother getting PC3700 RAM.

As for the Ratio selection for your RAM speed:  That's the synchronous/asynchronous operation I was talking about.  For example, if your CPU FSB is set to 200MHz (for an xp3200) and you only have PC2100 RAM, you can set the ratio to 66% and your memory FSB will run at 133 (266)Mhz for it's optimum setting.  It's a setting that allows you to run slower ram with a faster cpu.

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radomirthegreatAuthor Commented:
Beef, I really can't help but thank you too much.  Thanks a lot.  My BIOS lets me go up to a 233MHz BIOS speed.  Just to go far off before closing the question, can I get a Duron and run at an asynchronous ram speed so that I can use PC3700 ram?  Will that be slower than using a Duron with a 100MHz FSB?

Also, how much does asynchronous clocking kill performance, and how high do I need to go (asynchronous) to have a faster PC than the standard (synchronous) ram speed of DDR266?

Thanks again,
Radomir Jordanovic

P.S. droswell, I'm really glad you tried to help.  Could you please type out some - or all - of the math that you used to figure out CL3 benefits?  I'm seriously interested.
Glen A.IT Project ManagerCommented:
Does your BIOS setup allow 233MHz in both the memory and the cpu FSB speeds?  Curious.

You can get a Duron and run the processor asynchronously from the RAM -   as far as performance goes -  your best bet would be sisoft sandra or 3dmark or something to check.  I know that running 333MHz RAM with a 266MHz cpu speed results in a loss of performance.  (333memory speed and 266MHz cpu speed is lower performance than 266memory speed and 266cpu speed - go figure) but whether or not 200MHz cpu speed and 400MHz memory speed would make a difference, I don't know . . .  only benchmarks would tel you.

radomirthegreatAuthor Commented:
My CPU FSB can only be taken up to 200MHz.  That's a bummer.  I haven't done it, and I hope I'll stay sane enough to keep away from that.  All I did was press down and hold the Page Down key to see how far up the FSB can be set.  Should I really consider overclocking a 2.2GHz XP 3200?  Nah...  I can, however, get an XP 3000 with a 333MHz FSB speed.

How do you figure out the performance loss of DDR400 ram running at 266MHz?

Side note:  One time, I took up my FSB to 158MHz.  The PC wouldn't start, so I simply reset the BIOS.  When I went back into my BIOS after resetting it, I noticed the CPU was clocked at 100MHz FSB.  Can I run it at 100MHz without worrying?  Why would I worry?  Except for performance loss, should I forsee anything else and stay away from it?  I'd really like to benchmark some asynchronous speeds.

Thanks again,
Radomir Jordanovic
Glen A.IT Project ManagerCommented:
>>How do you figure out the performance loss of DDR400 ram running at 266MHz?

Clock your system with it's cpu at 133MHz FSB (for 266MHz operation) and your RAM at 133MHz (for 266MHz operation) and then run sisoft sandra and cpumark or 3dmark.  Record the results.  Now change your memory settings to 400MHz operation , keeping the cpu the same.   Rerun the tests and compare.  keep the settings that give you the best performance.

And yes, you can run it at 100MHz. . .  but why would you ever want to??  You may not see a performance loss in most of your apps, but you certainly would for games.

As for 158MHz FSB for you 133MHz cpu -  that's not terrible, depending on the cpu.  You may want to try the benchmark tests with your system running at 150MHz for the CPU (for 300MHz operation instead of 266MHz) and 150MHz for your memory -  see what sisoft sandra and cpumark / 3dmark tell you.  You might find it the best overall performance level for your pc.  it only mildly overclocks the pci bus (to 37.5) so it shouldn't be bad there.  

radomirthegreatAuthor Commented:
I'd want to do that to test the benefit of asynchronous ram speed.

Thanks again!

At 158, the PC just kind of sat at a dead standstill.  It didn't beep nor boot.  I don't think I should run at that... The PC also locked at 150MHz FSB.  So far, I've found I can run at a stable speed of 1.8GHz.  I haven't done anything with voltages, though.
Glen A.IT Project ManagerCommented:
so what's the highest FSB you can run with then?  Moving up from 133MHz in 1Mhz increments?  Start there, move up until it locks, then move back one.
radomirthegreatAuthor Commented:
By the way, I just went to my BIOS and set the FSB to 100.  It seems that, at 133/133, the system is more than twice as fast than 100/400.  Maybe the difference is too much?

Also, when I tried to go to 100, I went too far and ended up on 232!  Then, I went to 100 by going to 233!  Whoo hoo!  How did that happen?

My PC locks at 150.  I don't think I want to overclock that much.  I'm running at 134/134 right now.  It's very good.
Glen A.IT Project ManagerCommented:
well, the main thing is where it's good. . .  
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