The overclocking utility on my motherboard has a feature which lets me decide the CPU to DRAM Freq. Ratio. There are 4 settings. 2:1, 3:2, 6:5, 1:1. I have a P4 2.6 @2.9 800FSB and 512MBx2(1GB) of DDR400 PC3200. The frequency ive overclocked the CPU to is 222(originally 200). Could someone please explain what this ratio does? Also which one ud recommend.

Zo

The ratio helps when running lower bus speed RAM with a higher FSB CPU, or to help with overclocking.

Ideally, you should run 1:1 ratio so that the RAM & CPU are in sync.

At 2:1 ratio, your RAM bus would be running at 50% of the CPU bus, but you'd be able to run PC1600 (DDR200) RAM with your 200MHz (800FSB) CPU...at 3:2 it would be running at 66.66% for PC2100 (DRR266)...at 6:5 it would be at 83.33% for use with PC2700 (DDR333).

When overclocking, your RAM may hold your CPU back, so if you were to change the ratio to 6:5, you could raise the CPU bus up to 240MHz & your PC3200 RAM would still be running at 200MHz.

ASUS A7N8X-X
Athlon XP 1800+
8.5 x 200MHz
1024MB PC3200 2.5-3-3-7
Asus A9550GE/TD 128MB
WinME/WinXP Pro SP2

so which ratio should i choose for my specific RAM?

Zo

1:1 is the perfect ratio for all ram

Why can't we put questions here?

thanks a lot.

Zo

Yes, 1:1 is what you should always strive for, but since you have your CPU o/c'd to 222MHz, your PC3200 RAM may not be able to handle that speed. So you'd either have to back off on the o/c, or change the ratio to 6:5. That will put your RAM at 185MHz & should allow for an even higher CPU FSB (240MHz+).

ASUS A7N8X-X
Athlon XP 1800+
8.5 x 200MHz
1024MB PC3200 2.5-3-3-7
Asus A9550GE/TD 128MB
WinME/WinXP Pro SP2

thanks guys. 1:1 seems to be working fine. ill try o/cing it more once i get a new psu.

Zo

So what would you suggest in this case? Overclock the cpu?

Number of CPUs 2 (1 Physical)

CPU#1 APIC ID = 0
Name Intel Pentium 4 640
Code Name Prescott
Specification Intel(R) Pentium(R) 4 CPU 3.20GHz
Family / Model / Stepping F 4 3
Extended Family / Model 0 0
Package LGA775
Core Stepping N0
Technology 0.09 µ
Supported Instructions Sets MMX, SSE, SSE2, SSE3, x86-64
CPU Clock Speed 2800.0 MHz
Clock multiplier x 14.0
Front Side Bus Frequency 200.0 MHz
Bus Speed 800.0 MHz
L1 Data Cache 16 KBytes, 8-way set associative, 64 Bytes line size
L1 Trace Cache 12 Kµops, 8-way set associative
L2 Cache 2048 KBytes, 8-way set associative, 64 Bytes line size
L2 Speed 2800.0 MHz (Full)
L2 Location On Chip
L2 Data Prefetch Logic yes
L2 Bus Width 256 bits

CPU#2 APIC ID = 1
CPU Name Intel Pentium 4 640 (logical unit)


Mainboard and chipset
Motherboard manufacturer ASUSTeK Computer INC.
Motherboard model P5ND2-SLI, 1.XX
BIOS vendor Phoenix Technologies, LTD
BIOS revision ASUS P5ND2-SLI ACPI BIOS Revision 0605
BIOS release date 05/06/2005
Chipset nVidia nForce4 SLI Intel Edition rev. A1
Southbridge nVidia nForce4 MCP rev. A3
Sensor chip IT 8712

Memory
DRAM Type DDR2-SDRAM
DRAM Size 4096 MBytes
DRAM Frequency 166.7 MHz
FSB:DRAM 6:5
CAS# Latency 4.0 clocks
RAS# to CAS# 5 clocks
RAS# Precharge 5 clocks
Cycle Time (TRAS) 15 clocks
Bank Cycle Time (TRC) 19 clocks
# of memory modules 4
Module 0 Corsair DDR2-SDRAM PC5300 - 1024 MBytes
Module 1 Corsair DDR2-SDRAM PC5300 - 1024 MBytes
Module 2 Corsair DDR2-SDRAM PC5300 - 1024 MBytes
Module 3 Corsair DDR2-SDRAM PC5300 - 1024 MBytes

Software
Windows version Microsoft Windows XP Professional Service Pack 2 (Build 2600)
DirectX version 9.0c