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BIOS setting "Memory over voltage" shows value in red

Discussion in 'Overclocking' started by Maurice Batey, Mar 3, 2010.

  1. In the BIOS Setup 'Ai Tweaker' menu of my Asus P5QL/EPU motherboard I
    just happened to notice that the BIOS setting "Memory over voltage" is
    shown as "2.10000" in *red*.

    I find the red colour scary. Why red?

    Would I lose anything by changing the setting to 'Auto'?
    (What are the implications of doing so?)

    Or perhaps reduce by increments until it is no longer red?

    N.B. I have never gone in for 'overclocking'. I just happened to
    notice the red when scrolling through the Seup menus.

    There is 4GB of Corsair Dominator dual-DDR2 1066MHz RAM.
    Maurice Batey, Mar 3, 2010
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  2. Maurice Batey

    PvdG42 Guest

    It's telling you that you've exceeded the "normal" voltage by some arbitrary
    amount. You might try reducing the voltage to, say, 2.05 and see if your PC
    is still stable. You set it to 2.10 for some reason, correct? Was the PC
    unstable when the BIOS setting was "Auto"?

    More voltage means more heat and more stress on the component in question.
    Thus, shorter component life. As a practical matter, the "shorter life" will
    still probably exceed the useful (until replacement due to obsolescence) by
    a lot, so why worry?

    It's far more important that your PC run stable and not lose valuable data,

    If the red bothers you that much and/or you have heat issues, reduce the
    voltage a bit at a time, then run thorough stability tests (Memtest, etc.)
    until you're back in the "normal" range and still *stable*. Remember that
    the BIOS setting for "red" is generic and your memory's recommended voltage
    range may well be different, I.e. the memory spec may say 2.1 is OK.
    PvdG42, Mar 3, 2010
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  3. So reducing the voltage may cause some malfunction?
    I didn't touch the setting. It's how it was from new.
    Haven't tried 'Auto' - because I don't know what 'Auto' implies!
    The system has been behaving perfectly. It's the figure being in
    *red* that scared me!
    Not familar with 'stability tests', and don't know what 'normal'
    range' is.
    Don't understand 'setting for "red" is generic'.

    How does one find what the memory's recommended voltage range is?

    The BIOS manual says:

    "Memory Over Voltage (Default: Auto)
    Allows you to set the memory over voltage."
    The value ranges from 1.85000V to 2.24375V with a 0.00625V
    interval. Configuration options: [Auto]"

    So is 'Auto' a safer option than arbitarily reducing the voltage
    figure? How does 'Auto' work here?

    Sorry to be so dumb here, but it's an area of PC's that I have never
    dabbled in.

    Many thanks for responding; much appeciated...
    Maurice Batey, Mar 3, 2010
  4. Maurice Batey

    peter Guest

    the DDR2 Dominators run at 2.1 Voltage
    you need to adjust a setting on your mobo for the BIOS to accept that voltage
    without thinking it is overvolted(?)
    The normal voltage for that board is 1.7v
    See this website

    your manual should tell you where that jumper is located
    there usually is a diagram that points out the switches


    If you find a posting or message from me offensive,inappropriate
    or disruptive,please ignore it.
    If you dont know how to ignore a posting complain
    to me and I will be only too happy to demonstrate :)

    peter, Mar 3, 2010
  5. The PSQL/EPU manual says - of 1066MHx DDR2 RAM:

    "If you install a DDR2-1066 memory module whose ?? is
    DDR2-800, ensure you set the 'DRAM Frequency' item in the BIOS to

    I have checked that and it already has that setting.

    I cannot find any reference to "OV_CPU" in the BIOS manual.

    Are you saying there is some jumper that has to by physically modified
    on the motherboard?
    Maurice Batey, Mar 3, 2010
  6. It also says - for Memory Over Voltage:

    "Min = 1.85V Max = 2.24375V"
    Maurice Batey, Mar 3, 2010
  7. Maurice Batey

    Paul Guest

    The nominal voltage for DDR2 memory is 1.8V. The JEDEC spec
    has a tolerance on the nominal voltage, of perhaps +/- 0.1 volts.
    (Just going by what I see in a Kingston data sheet.)
    That tolerance is intended to cover the accuracy of a voltage
    regulator used to feed the DIMM. The regulator puts out 1.8V,
    and is allowed to be off by as much as 0.1V.

    Enthusiast RAM sometimes requires extra voltage, to meet
    timing and frequency specifications. You can take
    memory chips that aren't intended to run at that speed,
    feed them extra voltage, and get more performance from them.
    The Corsair memory could be a product like that. In the
    table here, I can see the specs for some Dominator brand



    Speed Rating Tested Speed Size Tested Latency Tested Voltage Performance Profile
    PC2-8500 1066Mhz 4GB Kit 5-5-5-15 2.1 EPP
    (2 x 2GB)

    SPD Speed SPD Latency Package Fan Included
    800Mhz 5-5-5-18 240pin DIMM No

    The term "EPP" means that the SPD chip on the DIMM, contains
    additional information about setting up the DIMM. The normal
    JEDEC SPD table doesn't contain a field for "overvolting". The
    EPP profile does. You can get a copy of the EPP specification
    by clicking a link here (archived copy of spec). This spec
    covers DDR2.


    On page 13, I see this. If you use a copy of CPUZ from cpuid.com,
    you may be able to view the EPP profile information. If CPUZ shows
    a voltage coming from the SPD table, that is what the BIOS could be

    Table 9. Voltage Level Field
    Voltage Level Example Hex Values
    1.8V 00h
    1.9V 04h
    2.0V 08h
    2.1V 0Ch
    2.2V 10h
    2.3V 14h
    2.4V 18h
    2.5V 1Ch

    The purpose of recording 2.1V in the EPP, is to ensure the memory
    meets 5-5-5-15 at DDR2-1066. As a user, when you start the motherboard
    for the first time, the memory setting might be Auto. If the BIOS
    supports EPP profile reading, it will immediately set the voltage
    to 2.1V, as specified in the table. This allows the motherboard
    to run the RAM at the manufacturer specifications immediately.

    A user is allowed to adjust the settings of their enthusiast memory
    manually, via the BIOS menu. A smart thing to do, is to gradually
    reduce the Vdimm setting, one voltage step at a time, and test
    for stability after doing so. If you encounter memory errors in
    your testing, then bump the voltage up one notch.

    If you misadjusted the memory so badly, that the motherboard could
    no longer POST, either the motherboard auto-clearing function or
    using the "Clear CMOS" jumper would restore control of the motherboard.
    Always unplug the computer if using the "Clear CMOS" jumper, for

    Tools for testing, include memtest86+ from memtest.org, and the
    usage of Prime95 (mersenne.org/freesoft) stress test while in Windows
    (or Linux). No errors are acceptable in either testing situation.
    For memtest, I use two passes as "enough testing". For Prime95,
    I accept 4 hours of error free stress testing as enough. After that,
    I use the computer, until there are signs that the settings are still
    not right. (For example, some 3D games will misbehave, when there are
    memory errors.)

    Back in the days when ECC memory was more popular, you could rely
    on the memory subsystem to detect marginal memory behavior (the
    odd error). But without ECC on most desktop memory, you can run
    stress tests, but when actually using the system, you're largely
    blind as to when memory errors are happening.

    I don't see any mention of EPP profile support in the description here
    of the BIOS, but there must be support, for the motherboard to have
    applied 2.1V as seen in the EPP for that RAM. If you enter the
    BIOS and use manual settings for the memory, you should be able
    to adjust that (and test after each adjustment). Don't boot Windows
    right away, after making a change, as you can actually corrupt
    your Windows installation if bad memory is present on your system.
    (Writing back a corrupted registry...)


    So the memory you bought is rated for 2.1V operation. JEDEC standard
    voltage for DDR2 is 1.8V. You can drop the voltage, until you get
    to the point that you're detecting errors while doing the various
    memory tests. Corsair apparently feels the memory will survive
    just fine on 2.1V.

    If you're curious about what kind of voltage a DDR2 memory chip can take,
    take a look at PDF page 23 here. This Micron chip can take 2.3 volts
    as the voltage level before there could be long term damage. So
    2.1 volts is still a bit less than that value.


    The Asus coloring scheme, is intended to show you the rough operating
    range being used. The "red" is to alert you to the fact that
    the JEDEC nominal value is not being used. You then rely on
    your other documentation, as to what to do.

    Paul, Mar 3, 2010
  8. No - I have the P5QL/EPU manual PDF file, and could not find any
    reference to EPP. but it's interesting to note you think there must
    be support in there.
    The supplier of the PC have said they do not change any of the
    BIOS settings, so the only way the 'memory over voltage' setting
    could have changed to 2.1V (and the DRAM Frequency setting to
    "DDR"-1066MHz?) must be as you conjecture.
    If that's all that it's trying to say, then I shall leave things as
    they are - assuming the setting of 2.1V is not a hazard of any kind.
    Here are some postings on subject I found on the 'net:


    "The cause of my issue was the BIOS and voltage of RAM. When my
    RAM was running @1066MHz the system became unstable and
    crash happened. I contacted MSI technical support for the
    issue and I updated the BIOS two times and increased RAM
    voltage from 2.0V to 2.1V ... After BIOS upgrade and increasing
    of voltage I not facing any crashes, hangs or BSoD for some
    I think the main reason of my problem was BIOS compatibity of
    1066MHz DDR2 and voltage."


    In my PC i have 2 sticks of DDR2 1066MHz Corsair Dominator
    Now this profile can only be achieved by manually setting the
    DDR2 voltage to 2.1V in the BIOS and it will automatically
    overclock the rest, which is cool, and fully in line with
    Corsair's recommendations for these sticks.

    Everything works fine, but PC Probe II tells me that the DDR2
    Voltage is 2.14V. I know that seems menial, but the .04V means
    the difference between a blown DRAM chip and a healthy one and
    since i have just RMA'd 2 faulty sticks clocked at the same
    settings as above (same make of sticks and everything) I am
    worried that maybe my voltage controllers (or whatever these
    things are called) are faulty? Or is it PC Probe overestimating
    such values?
    I'm a tad worried because i do not want to blow these
    sticks too!"

    "Try another voltage reporter, eg CPUID Hardware Monitor, as a
    Your bios is what you should trust. I wouldn't worry about
    the monitoring software. Even if you were at 2.14v you are quite
    2.2v is he highest safe value for prolonged use. Though some
    manufacturers will put them up to 2.3v, DDR2 in general is made
    to handle it up to 2.2v. As long as your system is perfectly
    stable you should be fine.
    0.04 V doesn't make a difference. Most DDR2 can easily
    handle 2.2V. My OCZ platinum is guaranteed to run at 2.2V.
    Corsair is a top RAM manufacturer, so no worries."

    Many thanks, Paul!
    Maurice Batey, Mar 4, 2010
  9. Have run cpu-z, and the SPD tab shows:
    (In slots #1 & #3):
    DDR2 2GB
    PC2-6400 (400MHz)
    CM 2x2048-8500C5D

    SPD Ext: EPP 1.0

    Timings Table:
    JEDE #1 JEDE #2 EPP #1
    Freq: 270MHz 400MHz 533 MHz
    Voltage: 1.8V 1.8V 2.100V

    (Had to write this down and type by hand, as cpu-z runs on Windows
    and I work on Linux!)

    Does all that make sense?
    Is there any other info that would help show all is OK?
    Maurice Batey, Mar 4, 2010
  10. Maurice Batey

    Paul Guest

    EPP #1 says "533 MHz" and that is support for DDR2-1066.

    You can see the two JEDEC entries, can only mention 1.8V,
    as that is the JEDEC nominal value.

    It means, as you would have expected, that the Corsair RAM
    has an EPP profile present on the DIMM. It still doesn't
    tell us though, whether the motherboard supports EPP.
    I don't know of a way to prove it, other than to find it
    mentioned in the motherboard manual. (I don't think CPUZ
    will tell us whether the motherboard knows about EPP.)

    I could probably suggest ways you could test for support
    of EPP yourself, but at this point, why mess up your
    system ? :) If you're happy with the way it is working
    right now, and don't want to do any more testing and
    tweaking, just leave it.

    Paul, Mar 5, 2010
  11. Does the re-setting (from presumably the default of AUTO) of:

    DRAM Frequency --> 1066MHz
    Memory Over Voltage --> 2.100000V

    not indicate that it *does* support EPP?

    (The supplier of this PC say they did not make any changes to the
    BIOS settings - though I am pressing them on this point, as it was
    they who fitted the 1066MHz RAM..)
    If there was a method that would not irretrievably mess up my
    system, I might be curious enough to try it!

    Maurice Batey, Mar 5, 2010
  12. Maurice Batey

    Paul Guest

    On thinking about it, I don't see any easy way to verify whether the
    BIOS supports EPP.

    I've been searching for evidence of EPP support, and generally
    it seems to get mentioned in adverts for Nvidia chipset boards.
    I suppose this is only natural, as Nvidia and Corsair were the
    first two to support EPP. Other than that, I don't seem to see
    it listed as a feature in the feature section of the manuals.

    The thing is, if Vdimm is set to "Auto" in the BIOS, you have no
    way of reading out the value it is using. You'd need a utility
    of some sort, running in Windows, to figure it out. Or, you
    could use a multimeter, and (somehow) figure out where to probe
    to measure Vdimm.

    My motherboard has a whole bunch of voltages that can be adjusted,
    but only seems to have four voltages measured on the hardware
    monitor. So I don't have a way to measure the actual Vdimm
    delivered, using just the motherboard. I think I'd need
    a multimeter, if the BIOS was set to "Auto", to figure out
    what it was actually using.

    The information exists. There is a hardware register somewhere,
    that is used to control Vdimm, and that means there should be
    a way to read it out. But if no one designs a utility to do that,
    then it is going to be pretty hard to figure out.

    Paul, Mar 5, 2010
  13. Maurice Batey

    ~misfit~ Guest

    Hi Paul, Maurice. Sorry to butt in on your conversation. I think it very
    likely that the mobo supports the feature. Unforunately it's hard to find
    out on Google as EPP also applies to parallel ports and most of the search
    strings I could complie ended up with hits that applied to this. Even the
    reviews on overclocking sites I checked mentioned 64-step vDIMM adjustment
    but nada about EPP w/r/t vDIMM.

    I even went to ASUS' site and downloaded their manual for the mobo but it
    isn't mentioned in there. However, as someone who's used a lot of Asus
    boards in the past to build machines for gamers who insist on having hi-spec
    RAM (even though they wouldn't know the difference from standard RAM...)
    I've run into trouble with modules in the past that require
    higher-than-default vDIMM.

    I can't remember the exact details now but on one build the machine kept
    crashing before I could even get into BIOS to raise the vDIMM. It was a C2Q
    so it's not ancient history. Running Corsair RAM. I think that the SPD told
    it to set the speed at a rate that it couldn't sustain at default vDIMM and
    it wouldn't run long enough for me to change vDIMM. I ended up using a stick
    of proper RAM to set the vDIMM to 2.1V, then shutting it down quickly and
    putting the wank RAM back in. ('Wank ram' because IMO it's only good for
    bragging rights, the money's usually much better spent elsewhere when
    building a new machine when it comes to return on investment. Still, the
    customer is always right, even when they tell me I'm wrong. :-\.)

    I did write a rather scathing email to Asus at the time complaining about
    the issue but I doubt that they changed to using EPP on the strength of just
    the on email. It does seem that it's the only answer to Maurice's query and
    IMO it's a good thing.

    However it's always been my policy when building machines for myself (or
    when speccing them myself) to always run RAM that only uses the default
    vDIMM. I've seen too many sticks of 'enthusiast RAM' die just out of
    warranty to ever want it in a machine of mine, or a machine that I've built
    and am likely to be supporting unless it's been asked for and my
    protestations to the contrary have been over-ridden.
    ~misfit~, Mar 7, 2010
  14. Maurice Batey

    Paul Guest

    That was common on some of the older boards. You had to tell a person
    to get a stick of "slow" RAM, so you could get the BIOS running, and
    make any adjustments to the settings. If the CMOS battery ever dies,
    and causes the settings to be lost, the same bootstrap procedure
    with the "slow" RAM might be needed all over again. It's kind of a curse.

    I expect the solution to this, was for Asus and the other companies, to
    run a bit more Vdimm without telling anyone. That is the quickest way to
    solve it. Some DIMMs come without the top speed setting stored in the SPD,
    and that is a second way to solve it (from the DIMM maker's end of things).

    I think all the RAM I have in the house here, is low voltage stuff. So far,
    I haven't been stuck getting a board to POST.

    And the companies making the memory, can actually make it without huge
    Vdimm boost. Look at what happened to DDR3 when the Intel Core i7 came
    along. Plenty of 1.65V RAM showed up, able to meet the Intel max spec.

    Paul, Mar 8, 2010
  15. Seems the only explanation. (I'm stll awaiting a reply from ASUS
    on this...) Thank you for your input, Shaun - much appreciated....
    That's what I did and found (or rather, didn't find!).
    With hindsight, that would be my policy, too - but when I ordered
    the PC I didn't realise that the higher frequency RAM needed to run
    at 2.1V rather than the usual 1.8V.
    The Corsair RAM does come with a 'lifetime waranty', which sounds

    So far, I am not aware of any problems. It was the accidental glimpse
    of the Memory Over Voltage "2.1V" setting in *red* that started me
    asking questions!

    Perhaps I should do a check with Memtest/Prime95?
    Maurice Batey, Mar 8, 2010
  16. Well, I installed memtest86+b V4.00 and let it loose. OK for 3-4 mins,
    then the foot of the screen went red with a list of error reports.

    Then quiet again, then more red - as if it found problems in a cluster.

    After 4 hours it had found 320 errors, and I closed it down for the night.

    So, although the system appeared to have been working well for 2 months, the
    RAM is suspect, so I guess I have to return the PC for a warranty repair (and I
    shall try to get the RAM replaced by normal-speed RAM...).

    Is there an alternative to returning it, I wonder?

    Would it be worth trying some adjustment? For example, increasing/decreasing
    the Memory Over Voltage from 2.1V?

    Another thing I noticed in the Ai Tweaker menu settings was the only other
    setting that was not 'Auto': FSB Frequency, which is set at 333. Does that
    look correct for 1066MHz RAM? I have no idea of its relaionship with the other
    Maurice Batey, Mar 9, 2010
  17. Maurice Batey

    Paul Guest

    FSB Frequency is the input clock to the CPU. That clock, times its internal
    multiplier, gives the core frequency. I don't recollect what your processor is,
    so I can't make a concrete example.

    If the processor is FSB1333, that is the bus transfer rate. The Intel bus is
    "quad pumped" and that means it transfers four items per clock cycle. If
    we take your 333MHz number and multiply it by four, that is where FSB1333
    comes from.

    The AI Tweaker was set to manual, so they could get at the DRAM setting.

    You have a "DRAM Frequency" setting, and that probably reads DDR2-1066
    right now.

    In the chipset section is the "DRAM Timing Control" setting. Setting
    that to [Manual] exposes the memory timings.

    tCL 5
    tRCD 5
    tRP 5
    tRAS 15

    As an experiment, you could try changing those to 6-6-6-18, then
    run memtest again. That is loosening the timing and making it
    easier for the memory to pass.

    The purpose of doing that test, is to see if the fault will go
    away or not. You can return those to their previous setting
    (5-5-5-15 or all Auto, whatever they were using), when you're
    finished testing.

    I wouldn't adjust the Vdimm voltage, as you're already using 2.1V
    and there is no point is adding to that.

    Depending on what your testing shows, may help you decide whether
    to return the system or not. I don't think relaxing the timing
    is going to make that much difference to your overall performance.
    If the memory errors are still there, then it is either the RAM
    at fault, or some other setting is off a bit.

    Another setting in the DRAM Timing Control, would be Command Rate.
    1T is tight, while 2T is loose. Left at Auto, I expect the BIOS
    can probably figure out the correct value to use. You can verify
    in CPUZ, what was used.

    I've had several batches of RAM fail, so having a RAM failure
    of some sort wouldn't be unusual. The last module I had fail,
    one chip died completely and delivered garbage for its entire
    contents. That makes plenty of scrolling errors in memtest.

    Paul, Mar 9, 2010
  18. Intel Core 2 Quad Q8300 2.50GHz 1333MHz FSB/4MB cache
    Sounds an interesting thing to do, but as this PC is only 2 months
    old and still under warranty, rather than tinker in areas that I'm
    not familiar with I think I'll lean on the suppliers to take it back
    for 'repair'.
    (Of course, they may suggest a similar adjustment first...)

    What I find odd is that - despite the plethora of memtest errors, the
    system continues to perform meticulously.
    But I'm backing up more often...

    Many thanks once again, Paul. Much appreciated....
    Maurice Batey, Mar 9, 2010
  19. Maurice Batey

    Paul Guest

    If you want confirmation of what memtest86+ is finding, you should
    give Prime95 (stress test option) from mersenne.org/freesoft a try. If
    your memory was really as fault free as you propose, then you should be
    able to run that for four hours without a problem. It will start
    a thread per core, and a thread will stop on the first error it

    On my other systems, I found it to be a pretty good indicator of
    system health.

    I've had that program stop in as short a time as 0.5 seconds.

    I have one 3D game demo here, that if there are memory errors, some
    of the bots start to misbehave. They go off to one side of the map
    and just stand there. So I have seen verification, that what the
    other tests see, is really there. The funny thing is, the game
    hardly ever crashes, but you do see bizarre behavior when the
    memory is not completely stable. Since I put together the DDR2
    based system I'm on now, I've stopped seeing those things.

    If you let a computer sit idle in the desktop, it might take
    100 hours of observation before there is a symptom. Testing with
    a stress program, shortens that interval considerably. One of the
    reasons for doing all the test cases, when a system is new, is to
    make sure that any initial "merchandise returns" can be executed
    before it is too late. You don't want to leave it sitting idle
    for 10000 hours, only to find a problem the first time the
    machine sees a bit of stress. Better to thrash the machine
    while it is in the return period. The computer is, after all,
    designed to run at 100% load, and the cooling system and
    power supply should have the capacity to do that. Otherwise,
    the system builder didn't do their job.

    Paul, Mar 9, 2010
  20. No - I believe it! W.r.t. Prime95, I was inclined to wait until the
    memory problem is sorted out, as running it before then
    would presumably inevitably come across problems probably related to
    the dodgy RAM, so would not tell me anything new (or would they?).
    Does Prime95 try to diagnose a situation, or does it just throw
    its hands in the air and say "Something wrong"?
    But I don't propose that! If memtest says the memory is rubbish,
    then rubbish it is...
    (The only thing that puzzles me there is why the system doesn't
    display symptoms when it's not idling.)
    Yes, indeed.
    I had a '600W Quiet Quad Rail PSU' & 120mm case fan installed,
    plus a 'super quiet 22dba triple copper heatpipe CPU cooler'.
    Maurice Batey, Mar 9, 2010
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