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A7N8X Clarification

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May 2, 2003 2:56:10 AM

As we all know, the A7N8X has a new Dual Channel DDR feature. Unfortunately, the board DOESNT seem to provide a way of confirming that the computer is in fact running in Dual Channel mode. is there a way i can tell if it is or isnt running in this mode?

Also, if somone could be so kind as to explain some details about o'clocking. i know HOW to do it. but i dont understand some of the concepts. example, when my board boots, it says that my mem speed is 200...now when i was looking through BIOS there was a note on the side where you could change the external bus freq. it said that the FSB is double the MHz. so, in theory, the 200MHz that my mem is clocked at is doubled and the PC3200 mem is in fact running at it full potential of 400MHz, and then IF it is in Dual Channel mode, THAT is doubled, and i am running 800 MHz FSB. (which is why i bought this baby)
then you have the whole factor of changing voltages...is more really better? and WHEN do i add more, and how much?
BTW... my cpu is an Athlon XP 1800 1.53GHz

have i asked enough? lol....
thanks a million...

Jesse

More about : a7n8x clarification

May 2, 2003 3:49:21 AM

You haven't done enough studies on your purchase. All nForce2 mobo don't have an indicator saying that you are in dual channel DDR mode. In case of A7N8X, install the RAM in slot 2 & 3 (the blue slots) and you are in dual channel DDR mode unless your mobo is defective. 200MHz of RAM bus frequency is correct, your RAM is DDR400. But your understanding on dual channel DDR is totally wrong. Dual channel DDR only double the memory bandwidth but not the bus frequency and definitely won't let you running 800FSB AMD CPU which is non-existence. If you want "800FSB" the only thing you can do is get yourself a P4 3.0/3.2GHz and i875P chipset mobo combo. So far AMD platform only up to 333FSB, which is 166MHz FSB DDR (or higher if you o/c). Finally... you bought the wrong thing which will never gives you a 800FSB perform.

Anything that can go wrong, will go wrong.
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May 2, 2003 3:54:48 AM

Okay, let's sloooow down. Before we get too carried away doubling everything that's read in MHz. Your CPU (the XP 1800+, specifically) runs the front side bus at 133MHz (with a multiplier of 11.5 makes 1530 MHZ for the internal clock) Since the Athlon can both send and receive at the same sime, that's 133 MHz in each direction. The end result? "266" MHz.
The memory, however, runs at it's own frequency. It can be either synchronous or asynchronous. Your PC3200 RAM is running at 200 MHz. It, like the CPU though is sending and receiving at the same time. This is where they get the term <i>Double Data Rate</i> (DDR!), and makes the rating 400 MHz.
The dual channel memory controller is different altogether. Think of the MHz figures like the speed of a car on the freeway. Dual Channel changes the <i>Bandwidth</i>, which is like adding lanes to the freeway. Now two cars can run the same speed <i>next</i> to each other instead of single file.
So what you're left with is a CPU FSB of 266MHz and a DDR speed of 400 MHz. As far as stock settings go, that's as good as it gets right now for AMD systems, so don't feel bad!
The A7N8X will show you if you're in dual channel mode starting with BIOS version 1004 (Motherboard versions 2.0 and above only- so far). It's available for download at ASUS' site.
As for voltage, that goes into the realm of overclocking, which is a whole different ballgame. All I can tell you is to read until your eyes hurt. There's a plethora of info and opinions out there.

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May 2, 2003 8:53:08 AM

You know... that's a good point. I have the MSI version of the nForce2 and by populating the correct memory slots, I just assumed it was running in dual channel mode... and i THINK that is correct. I believe the two slots are physically hooked up to the two different memory controllers, so it HAS to be working in dual channel mode. Not sure how to test that though. The Sandra memory benchmark seems to match what an nForce2 should do... so, other than that, I really donno!

As for the speed of your memory, you're a bit off thinking you have an 800 MHz. speed. You really just have two 200 MHz. memory busses... now that would be EQUIVALENT in terms of data throughput I think, but it's not really 800 MHz.

Adding voltage as you overclock is a tactic that often helps some but has quickly diminishing returns. Jumping the CPU voltage a tenth might help stabilize your CPU at a certain overclocked frequency, but it also adds heat. Real hard core overclockers will go nuts on CPU voltage, but I wouldn't recommend it for the average user.

Is your XP1800+ a T-bred? if so, it has a lot of overclocking potential, especially if it's a "B" stepping. If, on the other hand, it's a Palomino... well, not so much. Each has different voltages, so you need to know which you have before you start cranking up the voltage.

The older Palomino runs on 1.75 volts stock... The newer T-breds run on 1.5 or 1.6 volts. Again, adding a tenth or so is pretty safe if you've got a good heat sink and fan.

Lets see, the other areas you can change voltages are the chipset and AGP... but I've never been able to see much benefit with voltage increases on those areas... I don't really push video cards and it's pretty easy to keep memory running in spec as you overclock...

Scout
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May 2, 2003 4:54:24 PM

The crossbar memory architecture means that both controllers can access both channels; you just have to make sure that your RAM sticks are on different channels to get dual. Data throughput for any one device <i>will not</i> equal DDR2 800 performance, but current devices don't need that bandwidth anyways. Don't forget that RDRAM is a narrower 'highway' due to its 32-bit format, so comparing FSB speeds directly will be misleading. Where the benefit of the nForce2 architecture kicks in is during simultaneous accesses (think 3D gaming - CPU & AGP both want memory events). It's a bit like hyperthreading or running multiple processors; they're not much better at single tasks, but when the computer is being asked to do a bunch of things at the same time, woohoo :wink: !

<font color=blue>Learn from the mistakes of others. You won't live long enough to make them all yourself.</font color=blue><font color=green>
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May 2, 2003 4:58:50 PM

Oh, and one other minor clarification; DDR means that memory events occur at both the uptick and downtick on the clock cycle, rather than once every cycle as in SDR. A full-duplex data link is assumed in modern processors.

Hey, that raises an interesting question; is the CAS number based on the bus clock or the device clock? That is, does CAS 3 mean three ticks (up-down-up) or three cycles (up-down-up-down-up-down) in DDR?

<font color=blue>Learn from the mistakes of others. You won't live long enough to make them all yourself.</font color=blue><font color=green>
<i>Canadian Flight Safety periodical, ~1987</i></font color=green><P ID="edit"><FONT SIZE=-1><EM>Edited by Traqr on 05/02/03 01:03 PM.</EM></FONT></P>
May 3, 2003 2:10:50 AM

I had a question regarding how the memory is seen in the dual ddr mode.

If one has two sticks of 256meg memory in the dual ddr mode, is it seen as just 256meg since the processor gets access to both sticks at once. Or does it see it as 512 meg as in normal mode?

It would be logical if it were to only see 2 x 256 sticks = 256 meg since it is getting the goodie of both sicks at once through the dual controllers. Plus, does it really matter if it is only seeing the two sticks as one.
May 3, 2003 2:27:48 AM

For sure, two 256MB in Dual DDR results in 512MB of total memory capacity.
May 6, 2003 8:32:31 PM

I've seen several posts about a new a7n8x bios, but cannot find this new bios on the website and haven't seen it anywhere else. The latest they have is 1003. Anyone know where I can obtain it??
May 6, 2003 8:50:08 PM

Thanks, but I have v1.04. Guess I'll have to wait.
!