(G)MCH Frequency Latch/System Memory Multiplier Help!

LDiddy · Nov 27, 2008

Hello all! My last overclock was about several years ago with an nforce4 board. I am thinking about getting a Gigabyte board EP45-UD3P with a E8500 and some (2x2gb) g.skills ddr2-1066 ram. I was looking over at the manual and notices some terminology that I am not familiar with such as (G)MCH Frequency Latch and System Memory Multiplier. What are the differences between the two and what do they do?

(G)MCH Frequency Latch options are:
200mhz
266mhz
333mhz
400mhz

System memory multiplier options are:
2.00B
2.40B
3.20B
4.00B

2.00D
2.66D
3.33D

2.66C
3.33C
4.00C

2.50A
3.00A
4.00A

thanks for any help!

Ross · Nov 27, 2008

Latch freq is the NB strap, basically, internal NB timings. Lower is tighter. The separate MCH Latch settings in the Giga boards are basically redundant since you can pick mem ratio and the strap in the mem section at the same time.

C = 200 strap
A = 266 strap
B = 333 strap
D = 400 strap

So if you leave MCH Latch on AUTO and pick 2.00B from the mem options, you will have 1:1 on the 333 strap. Things seem to work better if you do leave the latch on AUTO, but if you did chose one manually, it just removes the other options from the mem selection. So if you set latch to 400MHz manually ("D"), the only mem options visible will be with the D strap options (2.00D, 2.66D and 3.33D). When latch is left on AUTO, all the mem options are available in the mem selection.

LDiddy · Nov 27, 2008

Ross said:
Latch freq is the NB strap, basically, internal NB timings. Lower is tighter. The separate MCH Latch settings in the Giga boards are basically redundant since you can pick mem ratio and the strap in the mem section at the same time.

C = 200 strap
A = 266 strap
B = 333 strap
D = 400 strap

So if you leave MCH Latch on AUTO and pick 2.00B from the mem options, you will have 1:1 on the 333 strap. Things seem to work better if you do leave the latch on AUTO, but if you did chose one manually, it just removes the other options from the mem selection. So if you set latch to 400MHz manually ("D"), the only mem options visible will be with the D strap options (2.00D, 2.66D and 3.33D). When latch is left on AUTO, all the mem options are available in the mem selection.

Thanks you so much for your responds! So if I got this correct, if I am at 400fsb with a System Memory Multiplier of 2.66C that would equate to DDR2-1064mhz (400 x 2.66 = 1064) at 200 on the Northbridge strap? BTW, where did you get this conversion from? Was it in the manual because I am unable to find it.

C = 200 strap
A = 266 strap
B = 333 strap
D = 400 strap

thanks

Ross · Nov 27, 2008

No problem and yes, your example is exactly correct. The conversion is shown in the BIOS info section (right side) when you are on the System Memory Multiplier option :beer:

(G)MCH Frequency Latch/System Memory Multiplier Help!

LDiddy

Registered

Ross

Senior Intel-lectual

LDiddy

Registered

Ross

Senior Intel-lectual

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