Newbie's question about setting RAM speed

[Jiayu]

Below is my PC information.
I have had this PC for a while. I remember the memory I bought is PC3200 from Crucial.
So, since A7N8X2.0 supports FSB400 and my RAM is DDR400, should I set it to run at 200MHz?
Do I have to adjust something, timing/voltage, if I do so?
Or, am I confused somewhere?

Thanks in advance

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Processor
Model : AMD Athlon(tm) XP 2500+
Speed : 1.84GHz
Model Number : 2500 (estimated)
Performance Rating : PR2665 (estimated)
Type : Standard
L2 On-board Cache : 512kB ECC Synchronous Write-Back (16-way, 64 byte line size)

Mainboard
Bus(es) : AGP PCI USB FireWire/1394 i2c/SMBus
MP Support : No
MP APIC : No
System BIOS : Phoenix Technologies, LTD ASUS A7N8X2.0 Deluxe ACPI BIOS Rev 1006
Mainboard : ASUSTeK Computer INC. A7N8X2.0
Total Memory : 1023MB

Chipset 1
Model : ASUSTeK Computer Inc nForce2 AGP Controller
Front Side Bus Speed : 2x 167MHz (334MHz data rate)

 

[Peter]

There is no such thing as "FSB400" or "DDR400". Both are actually 200 MHz w/ DDR transfers.

FSB is the (F)ront (S)ide (B)us of the CPU, nothing directly to do with the RAM, which is on a bus of its own. Speeds are independent on most chipsets, including yours.
For best performance, you should nonetheless set the RAM bus to the same speed the CPU bus runs at, to avoid synchronization penalties which make things slower.
So, with your XP2500+ running on 166 MHz FSB, you should run the RAM at 166 MHz too.