Confused about MCH and Memory speed

[mstefani77]

Can someone help explain the difference between the memory operating frequency and the MCH setting in the BIOS is? I'm using OCZ PC2 8500 memory which should operate at 533Mhz. So in the bios setup if I leave the MCH Frequency Latch and the memory multilier to Auto it shows me at 1066. I boot into windows and CPU-Z shows me at 533 Frequency.

Where I get confused is if I try to manually set the MCH and memory multiplier. When I try to set MCH manually I don't even see 533 as an option, it looks like 400 is as high as it goes. Really confused how these settings relate. Thanks for any info.

[Lsdmeasap]

Re: Confused about MCH and Memory speed

Memory Frequency is the ram speed, which is controlled by the memory Multiplier X FSB

MCH is the Northbridge, and the latches are straps it operates at like ram speeds. They all offer different memory multipliers, shown on the right in the BIOS by + ~ and so on symbols

You will want to try 333 or 400 and then use the setting right below that ram multi, to set the Ram to 1066

Like for example with a 333 FSB these are some setting you would use for 1066 ram speed

(G)MCH Frequency Latch...............: [333]
System Memory Multiplier ..............: 3.20
Memory Frequency (Mhz) ..............: 1065Mhz Ram freq. (Multiplier above 3.20 X FSB = 1065 RAM Freq)

Or
(G)MCH Frequency Latch...............: [400]
System Memory Multiplier ..............: 3.2
Memory Frequency (Mhz) ..............: 1065MHz (FSB 333 X 3.20 = 1065 Ram Freq)

Please see the guides I have posted, I know they may not mention P45 boards but they will help you understand those settings a little better >>>

http://forums.tweaktown.com/f69/gigabyte-x38-p35-p965-ds-dq-s3-overclocking-general-bios-tweaking-guide-26112/

And

http://forums.tweaktown.com/f69/memory-timings-explained-w-suggested-timings-memset-vs-bios-27283/

If you do need some help in overclocking, I can help you. If you decide you need some help please post your full specs and I will post a template for you to post back the settings you are trying that are not working for you. Then I will post you some suggested settings once you post back

[mstefani77]

Re: Confused about MCH and Memory speed

I guess what I'm still confused about is what's the difference between using a 400 MCH vs 333 MCH? The memory frequency seems to be determined by the FSB x the Memory Multiplier. But with the MCH at 333 or 400 the multiplier is still 3.2. So in the example above would I be gaining something in performance by using the 400MCH vs 333MCH?

[Lsdmeasap]

Re: Confused about MCH and Memory speed

Yes, the 400 strap runs the FSB at a much tighter set of timings so it would be better overall performance but will be less stable and take more tweaking.

A 333 strap is good to use as it allows more room for tighter ram timings and ease of getting stable, but those would only be to about 430 or so FSB, after that you should use 400 Strap

400 will take you some tweaking, but if you get it to run that is the better choice, what FSB are you running

[mstefani77]

Re: Confused about MCH and Memory speed

I'm not overclocking at all so just the default 333Mhz. I'll just leave it to Auto for now since it correctly sets the memory to 1066 on Auto. Thanks for the explanation that makes a lot more sense now. I was thinking MCH x the multiplier gave the memory frequency, thanks for clearing that up!

[Lsdmeasap]

Re: Confused about MCH and Memory speed

Ok. Auto is likely 333 anyway for the MCH Strap.

Ram Frequency = FSB X Memory Multiplier

Just so you are fully clear, that MCH Latch is Northbridge Strap and is just the freqency that the Northbridge will run it and does not affect ram speeds.

It does however matter when you are choosing a memory multiplier what Strap you are using as different memory Multipliers will be offered at different MCH strap choices

[ashwath84]

Re: Confused about MCH and Memory speed

hey guys i really need help here. i have a core2quad q9550 rated to run at 2.83 ghz (333x8.5). i am currently running it at 3.4 ghz (400x8.5). ok no problem here. i have 4x1gb kingston hyperx ddr2 1066 mhz memory modules. no matter what i try i just cant run the ram at the rated speed other than the default 800mhz. i even manually set the timings to 5-5-5-15 and dram voltage to 2.2v according to manufacturers' specs. i tried changing the ram multiplier in my bios so that the ram would run at 1066 (400x2.66), but the damn system just wont boot. i've tried it a number of times. it cannot run at any other speed higher than 800mhz or 960mhz. if there is any other voltage settings that has to be changed, please do let me know. my motherboard is a gigabyte ga ep45 ds3r mobo that uses a p45 chipset. thx.
Ashwath.

[Lsdmeasap]

Re: Confused about MCH and Memory speed

Try this, you need to get off the 400 strap line, so use a little above 400.

First of all, have you tested Each stick byitself with Memtest86+? >>>
Memtest86+ - Advanced Memory Diagnostic Tool

If not, please do so now, hate to have you get a headache trying to get things to work and find out a week later you have a dead or dying stick! Please test each stick one at a time in slot one with Stock speed set of 1066 using the proper multi, stock main timings, and set the rated 2.1-2.1 voltage

If all your ram tests out ok then try this and see if you can get anywhere. If you do not get anywhere, please post back exactly what settings you set that failed

MB Intelligent Tweaker(M.I.T.)
Robust Graphics Booster ...............: [auto]
CPU Clock Ratio ..........................:8
Fine CPU Clock Ratio.....................: .5
CPU Frequency ...........................: 3.417


Clock Chip Control
Standard Clock Control
CPU Host Clock Control..................: [Enabled]
CPU Host Frequency (Mhz) ............: 402Mhz
PCI Express Frequency (Mhz) .........:Set to 100

C.I.A.2 .................................:[Disabled]


Advanced Clock Control [Press Enter]
CPU Clock Drive...........................: <<< 800
PCI Express Clock Drive.................: <<< 900
CPU Clock Skew (ps)....................: <<<
MCH Clock Skew (ps)...................: <<<


DRAM Performance Control
Performance Enhance...................: [STANDARD]
Extreme Memory Profile (X.M.P.).....: Disabled
(G)MCH Frequency Latch...............: [333] << 400 may also work well, test both
System Memory Multiplier ..............: 2.66
Memory Frequency (Mhz) ..............: 1069Mhz
DRAM Timing Selectable ................: [Manual]

Standard Timing Control
CAS Latency Time........................5
tRCD .........................................5
tRP'...........................................5
tRAS..........................................15/18

Advanced Timing Control
tRRD...........................................3-5
tWTR..........................................3-6 (may need 8-12)
tWR............................................4-6 (May need 8-14)
tRFC...........................................52-65
tRTP...........................................3-6
Command Rate (CMD) ....................:2

Channel A
Static tRead Value.........................:7-12
tRD Phase0 Adjustment...................:<<< Leave for all below as well
tRD Phase1 Adjustment...................:Auto
tRD Phase2 Adjustment .................:Auto
tRD Phase3 Adjustment..................:Auto
Trd2rd(Different Rank)....................:Auto
Twr2wr(Different Rank)...................:Auto
Twr2rd(Different Rank)...................:Auto
Trd2wr(Same/Diff Rank)..................:Auto
Dimm1 Clock Skew Control...............:Auto ps
Dimm2 Clock Skew Control...............:Auto ps

Channel B
Static tRead Value.........................:7-12
tRD Phase0 Adjustment...................:<<< Leave for all below as well
tRD Phase1 Adjustment...................:Auto
tRD Phase2 Adjustment .................:Auto
tRD Phase3 Adjustment..................:Auto
Trd2rd(Different Rank)....................:Auto
Twr2wr(Different Rank)...................:Auto
Twr2rd(Different Rank)...................:Auto
Trd2wr(Same/Diff Rank)..................:Auto
Dimm1 Clock Skew Control...............:Auto ps
Dimm2 Clock Skew Control...............:Auto ps

Motherboard Voltage Control
Voltage Type.………... Manual
CPU
CPU Vcore….……….........................: All up to you, set what you KNOW works for sure or add more until you get things sorted out, then you can lower later. Maybe 1.3 or so, maybe less. Like I said all up to you and your chip.

CPU Termination…..... 1.200V*.......: <<< 1.3-1.4
CPU PLL…………………....1.500V*.......: <<<1.5
CPU Referen.…………....0.755V*.......: <<< Leave
CPU Reference2………,,0.800V*.......:<<< Leave

MCH/ICH
MCH Core…………….....1.100V...........: << 1.2-1.25
MCH Reference….…….0.800V...........; <<< Leave
MCH/DRAM Ref.…......0.900V...........: <<< Leave
ICH I/O……………….....1.550V............: <<< Leave
ICH Core…………...……1.100V............: <<< Leave

DRAM
DRAM Voltage ……....1.800V............: 2.1-2.2 << 2.1 may be all that is needed
DRAM Termination .…0.900V............: <<< Leave
Channel A Reference 0.900V............: <<< Leave
Channel B Reference 0.900V............: <<< Leave

Advanced Settings
Limit CPUID Max. to 3.....................: [Disabled]
No-Execute Memory Protect............: [Enabled]
CPU Enhanced Halt (C1E)................: [Disabled]
C2/C2E State Support....................: [Disabled]
x C4/C4E State Support..................: [Disabled]
CPU Thermal Monitor 2(TM2) ...........: [Enabled]
CPU EIST Function.........................: [Disabled]
Virtualization Technology................: [Disabled]