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Thread: MCH Voltage?




  1. #1
    Join Date
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    Default MCH Voltage?

    Hey all,

    I'm trying to get my E8400 (c0) stable at 4GHz with an EP45-DS4 motherboard and Corsair Dominator TWIN2X4096-8500C5D memory. It's almost stable at the moment, there are only a few crashes and the occasional BSOD. It passes memtest and Prime95 with small FFT's, and even passes Intel Burn Test, but fails Prime95 blend. The one thing, which I've read is pretty vital with a 33% overclock in FSB and with 2x2GB of memory at 1066MHz, which I haven't managed is a (decent) increase in MCH core voltage. I can increase it by about 0.06V, up to 1.16V, but at 1.18~1.2V it becomes unstable and any higher than that and it doesn't boot (no display for a few seconds and then resets). I've read that I could need over 1.25V, and I've never read of anyone having problems at such low voltages, so can anybody shed some light on why my MCH is so stubborn?

    Thanks,
    Shard.
    Last edited by Shard; 04-14-2009 at 07:51 AM.

  2. #2
    Lsdmeasap's Avatar
    Lsdmeasap is offline GIGABYTE Guru
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    Default Re: MCH Voltage?

    Did you try 1.24-1.26 directly? If not, please try them. If that does not work please try 1.05 MCH as in some boards this works better.

    If you have no luck, then you may need to bring your MCH Ref voltage down or up. What Vtt (Termination) are you using anyway?

    P45 NB Is Very tricky, that is why you seem to have issues. What tRD (Static tRead Value) and Memory Multi/Strap are you using as well as this could be the issue?

    Let me have a look at your full settings, that would be easier >>>

    This is Just a template I use to ask people their settings, pay no attention to the numbers in it, replace with yours

    CPU = Model #
    Motherboard = Model, Revision #
    BIOS Version =
    Ram = Brand, Model#, Part#, And or Link

    Code:
    MB Intelligent Tweaker(M.I.T.)
    Robust Graphics Booster ...............: Auto or Fast
    CPU Clock Ratio ..........................: 
    Fine CPU Clock Ratio.....................:.0
    CPU Frequency ...........................: 
    
    
    Clock Chip Control 
    Standard Clock Control
    CPU Host Clock Control..................: [Enabled] 
    CPU Host Frequency (Mhz) ............: Mhz
    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...............: [Auto]
    System Memory Multiplier ..............: 
    Memory Frequency (Mhz) ..............: 
    DRAM Timing Selectable ................: [Manual]
    
    Standard Timing Control
    CAS Latency Time........................
    tRCD .........................................
    tRP'...........................................
    tRAS..........................................
    
    Set all Suggested below to highest Values first.  Then later you can lower, one at a time, testing as you go
    
    Advanced Timing Control
    tRRD...........................................
    tWTR..........................................
    tWR............................................
    tRFC...........................................
    tRTP...........................................
    Command Rate (CMD) ....................:2
    
    Driving Strength Profiles
    Driving Strength ............................
    
    Channel A
    Static tRead Value.........................:6/7-10 333/B MCH - 8/9-12 400/D MCH
     tRD Phase0 Adjustment...................:Auto <<< 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.........................:6/7-10 333/B MCH - 8/9-12 400/D MCH
     tRD Phase0 Adjustment...................:Auto <<< 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
    
    CPU
    CPU Vcore….……….........................:Auto if not overclocking, if you are overclocking please do find and set your own voltages
    
    CPU Termination…..... 1.200V*.......: << If overclocking Please set to stock, Auto overvolts this way to much.  Optimal range for overclock would be 1.2-1.5 depending on Vcore, try to keep at least .1 under vcore.  Auto is fine if not overclocking
    
    CPU PLL…………………....1.500V*.......: << If overclocking Please set to stock, Auto overvolts this way to much.  Optimal range for overclock would be 1.5-1.65.  Auto is fine if not overclocking
    
    CPU Referen.…………....0.755V*.......: <<< .64% Of Vtt (Termination above) Auto Will set this correctly 
    
    CPU Reference2………,,0.800V*.......:<<< .67% Of Vtt (Termination above) Auto Will set this correctly 
    
    MCH/ICH
    MCH Core…………….....1.100V...........: << 
    MCH Reference….…….0.800V...........; <<< Leave
    MCH/DRAM Ref.…......0.900V...........: <<< Leave
    ICH I/O……………….....1.500V............: <<< Leave
    ICH Core…………...……1.100V............: <<< Leave
    
    DRAM
    DRAM Voltage ……....1.800V............: 
    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] Enabled if you use Vmware/Virtual PC
    
    Integrated Peripherals
    Legacy USB Storage Detect ..............[Disabled] *Note* Must be enabled to flash from USB

  3. #3
    Join Date
    Apr 2009
    Posts
    6

    Default Re: MCH Voltage?

    Yes, I tried 1.24 directly last night, it only managed to post but didn't boot, and at 1.28 it doesn't post which leaves little hope for 1.26. I'll try lowering it later, but I can't get 1.05 exactly, only 1.00 or 1.10.

    CPU = E8400, stepping C0
    Motherboard = EP45-DS4, Rev. A2
    BIOS Version = F9
    RAM = Corsair Dominator 2x2GB PC2-8500C5
    https://www.overclockers.co.uk/showp...odid=MY-148-CS

    Code:
    MB Intelligent Tweaker(M.I.T.)
    Robust Graphics Booster ...............: Fast
    CPU Clock Ratio ..........................: 9
    Fine CPU Clock Ratio.....................: 0
    CPU Frequency ...........................: 3.99 GHz
    
    
    Clock Chip Control 
    Standard Clock Control
    CPU Host Clock Control..................: [Enabled] 
    CPU Host Frequency (Mhz) ............: 444 Mhz
    PCI Express Frequency (Mhz) .........: 100
    C.I.A.2 .................................:[Disabled]
    
    
    Advanced Clock Control [Press Enter]
    CPU Clock Drive...........................: 800 mV
    PCI Express Clock Drive.................: 900 mV
    CPU Clock Skew (ps)....................: 0 ps
    MCH Clock Skew (ps)...................: 0 ps
    
    
    DRAM Performance Control
    Performance Enhance...................: [Standard]
    Extreme Memory Profile (X.M.P.).....: Disabled
    (G)MCH Frequency Latch...............: [Auto]
    System Memory Multiplier ..............: 2.40B
    Memory Frequency (Mhz) ..............: 1066
    DRAM Timing Selectable ................: [Manual]
    
    Standard Timing Control
    CAS Latency Time........................: 5
    tRCD .........................................: 5
    tRP'...........................................: 5
    tRAS..........................................: 15
    
    Advanced Timing Control
    tRRD...........................................: 6
    tWTR..........................................: 7
    tWR............................................: 8
    tRFC...........................................: 58
    tRTP...........................................: 6
    Command Rate (CMD) ....................: 2
    
    Driving Strength Profiles
    Driving Strength ............................: Auto
    
    Channel A
    Static tRead Value.........................: 8
     tRD Phase0 Adjustment...................: Auto
    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
    Dimm2 Clock Skew Control...............: Auto
    
    Channel B
    Static tRead Value.........................: 8
     tRD Phase0 Adjustment...................: Auto
    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
    Dimm2 Clock Skew Control...............: Auto
    
    Motherboard Voltage Control
    
    CPU
    CPU Vcore….……….........................: 1.40000V
    CPU Termination…..... 1.200V*.......: 1.200V
    CPU PLL…………………....1.500V*.......: 1.500V
    CPU Referen.…………....0.755V*.......: Auto
    CPU Reference2………..0.800V*.......: Auto
    
    MCH/ICH
    MCH Core…………….....1.100V...........: 1.160V
    MCH Reference….…….0.760V...........; Auto
    MCH/DRAM Ref.…......0.900V...........: Auto
    ICH I/O……………….....1.500V............: Auto
    ICH Core…………...……1.100V............: Auto
    
    DRAM
    DRAM Voltage ……....1.800V............: 2.100V
    DRAM Termination .…0.900V............: Auto
    Channel A Reference 0.900V............: Auto
    Channel B Reference 0.900V............: Auto
    
    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] 
    
    Integrated Peripherals
    Legacy USB Storage Detect ..............[Disabled]
    Last edited by Shard; 04-14-2009 at 08:53 PM.

  4. #4

    Default Re: MCH Voltage?

    yeah i have an e8400 co and a ga-ep45-dsq6. i fought for months to get it stable at 4ghz. It just won't do it. At 3.914 it is rock solid stable and the volts and temps are ridiculously low, but at 4.00ghz the voltages required started to shoot through the roof. It was extremely frustrating as the PC would boot at 4.3 ghz, but nothing I could do could stabilize it at and above 4.

    (i find it weird that you get more unstable by adding mch voltage. That is really really odd. Normally mch either helps or doesn't help, but it almost never ever hurts. Your mch ref seems a bit high too. 0.76 is stock on most gigabyte boards and I think a lot of people find max stability at 0.68 to 0.72)

    Anyway, it may not be what you want to hear, but CO chips just don't oc as easily as the E0 chips and there are a good number of CO owners who simply couldn't get to 4 ghz despite all the hoopla about the e8400. You may want to try 9x435 and see if you can get that stable instead of simply assuming that 9x445 is attainable.

  5. #5
    Join Date
    Apr 2009
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    Default Re: MCH Voltage?

    Quote Originally Posted by Sunburn74 View Post
    yeah i have an e8400 co and a ga-ep45-dsq6. i fought for months to get it stable at 4ghz. It just won't do it. At 3.914 it is rock solid stable and the volts and temps are ridiculously low, but at 4.00ghz the voltages required started to shoot through the roof. It was extremely frustrating as the PC would boot at 4.3 ghz, but nothing I could do could stabilize it at and above 4.

    (i find it weird that you get more unstable by adding mch voltage. That is really really odd. Normally mch either helps or doesn't help, but it almost never ever hurts. Your mch ref seems a bit high too. 0.76 is stock on most gigabyte boards and I think a lot of people find max stability at 0.68 to 0.72)

    Anyway, it may not be what you want to hear, but CO chips just don't oc as easily as the E0 chips and there are a good number of CO owners who simply couldn't get to 4 ghz despite all the hoopla about the e8400. You may want to try 9x435 and see if you can get that stable instead of simply assuming that 9x445 is attainable.
    It is 0.76, I just didn't bother changing the default values which Lsdmeasap put in. I'd still like to figure out what's up with the MCH voltage before I give up though, because like you said, this isn't normal behaviour for the MCH, so I want to make sure there's nothing up with that first.

  6. #6

    Default Re: MCH Voltage?

    prime blend is more a test on the ram and the fsb than it is a test of the cpu.

    focus on your ram settings. use a 2 multiplier and appropriate latch even if it means underclocking your ram (running your ram faster than your cpu doesn't give benefits anyway). use auto timings for the ram instead of the manufacturers. etc try and identify the problem essentially. but no i wouldn't look at the cpu settings, but instead the ram settings.

  7. #7
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    Default Re: MCH Voltage?

    Ok I decreased the MCH reference voltage to about 0.685V and it's been priming (blend) for over 40 mins now with no errors, which I think is the best I've managed at these frequencies, so it's definitely improved. I'll carry on decreasing the MCH ref until it's as stable as I can get it (which will hopefully be completely), but it still doesn't help me understand why increasing my MCH core makes it unstable!
    This is looking promising anyway so I'll give a stability report tomorrow I guess. Thanks for the help you two.

  8. #8

    Default Re: MCH Voltage?

    just so you know, the mch ref v stability curve is sort of like a sine wave. there is apoint where decreasing it makes it more unstable you know. but anectodal evidence suggests for most users 0.68 - 0.72 is about right, where the higher your FSB the lower the mch ref the board wants.

    Now just so you know: if you're running prime95 and one core fails whilst the other one keeps going, your issue is probably a vcore issue. if both cores fail it can be either a vcore issue or a fsb/ram issue depending on if its prime blend or fft and etc. thats kinda why people prefer prime to orthos. they are the same test usign the same math, the only difference is orthos is set up to stop regardless of if one core or two fails, meaning you kinda learn less from your mistakes.
    Last edited by Sunburn74; 04-15-2009 at 03:18 AM.

  9. #9
    Lsdmeasap's Avatar
    Lsdmeasap is offline GIGABYTE Guru
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    Default Re: MCH Voltage?

    P45 chipset is VERY Tricky, it may need more or less voltage then you would expect to need to use for any given setting. It all depends on your overall speed, ram spee, ram multi, tRD, and all other settings. Just keep in mind more is not always the answer as one would think, and even at the same ram speed/settings using a 2.00B or 2.00D ram multi for example can affect many things voltage and timing wise. One may need less MCH Core then the other, and that one could be the one you would expect to need more.

    MCH Ref must be set/changed properly. You do know this correct? TO set it you must set Vtt (Termination) to stock 1.20, then adjust your MCH Ref to what you want to try out. Then adjust Vtt Back up to what you want to use, MCH Ref will self adjust as you raise Vtt back.

    tRRD is WAY to high, and that can give you issues possibly. I do also note that you are using 1.20 Vtt, you need more then that for sure and once you set it properly you may not need so much Vcore

    Try these with your above listed settings (MCH Ref aside for now, Link in my sig on how to adjust if you are not sure) >>>

    CPU Termination…..... 1.200V*.......: 1.200V << Set 1.25-1.34 (1.28-1.3 likely good)
    CPU PLL…………………....1.500V*.......: 1.500V << Set 1.55-1.58


    MCH/ICH
    MCH Core…………….....1.100V...........: 1.20-1.24 (Should be good, more or less may be needed due to you using a B memory multi)
    ICH I/O……………….....1.500V............: Auto << Set 1.55-1.6
    ICH Core…………...……1.100V............: Auto << set 1.14-1.2
    Last edited by Lsdmeasap; 04-15-2009 at 01:52 PM.

  10. #10
    Join Date
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    Default Re: MCH Voltage?

    (i find it weird that you get more unstable by adding mch voltage. That is really really odd. Normally mch either helps or doesn't help, but it almost never ever hurts. Your mch ref seems a bit high too. 0.76 is stock on most gigabyte boards and I think a lot of people find max stability at 0.68 to 0.72)
    My board (although different chipset/model) behaves in exactly the same way. Increasing the MCH voltage causes more limitations for me.

    Another side to this is, we don't know all the "tweaks" and fixes Gigabyte introduce into various bios releases, so Its quite possible two identical boards with different bios versions could have different base/default values. Often we only know we increment a value from a base/default value, but as to what that is exactly is difficult to attain.
    GA-P35C-DS3R Rev2.0 F11 bios, E8200 (@3.0Ghz), OCZ DDR3 PC3-10666 Reaper 4GB (@1200Mhz), Xonar D1, 8800GTS 512, Corsair HX520 (Single 12volt line, Max 40A), WDC 3200aaks/5000aaks in AHCI mode, Vista 64 Premium.

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