unstable system Prime95

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

Hello.
I'm really new to homebuilding so I would really appreciate some advice.
I've recent;y put together a computer based around a Jeyway 694AS
motherboard which I bought second hand. It came with a Pentium III 700Mhz
and 256MB RAM.
The computer was very unstable. Giving Windows XP blue stop screens every
5 -15 mins so I decided to reduce the processor speed.
The bus thing on the motherboard was set at 133Mh so I lowered it to 100Mh
and made no other change.
This reduced the speed of the RAM which was at 133Mhz but by defauly it was
lowered to the bus speed of 100Mhz.
On boot up the processor was now reported at a Pentium III 550e Mhz
Anyway the computer was much more stable. I had it switched on all day with
no crashes.

So I decided to try Prime95s 'Torture Test.
However this always fails after a few mins by either hanging, getting a blue
screen, or the error 'fatal error - rounding was 0.49********, expected less
than 0.4'

The problem I have is there are so many variables which I don't properly
understand and I don't know which ones to change.
For instance:-
1) The RAM DIMMS have 133Mhz written on them. But when I lowered the
motherboard bus to 100MHz the memory speed was lowered by default. It is now
set at 100Mhz. The same as the 'host bus'. Should I raise the memory back
to 133?
2) Is the problem with the processor or with faulty memory?
3) By how much should I increase the core CPU voltage if at all?
4) Should I try lowering the bus speed to 66Mhz and underclock the
processor?
4 answers Last reply
More about unstable system prime95
  1. Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

    OraceHorse:

    > Is the problem with the processor or with faulty memory?

    Here's what I would do, bump the clock back to 133Mhz and run Memtest to
    see if it finds memory errors. If it does, replace the memory; if it locks
    up, try it at 100Mhz. If it still locks up, then it might be the
    processor.

    I wouldn't spend much money replacing components. For what you'll spend
    troubleshooting you could assemble or buy a low cost new system.
    --
    Mac Cool
  2. Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

    "Mac Cool" <Mac@2cool.com> wrote in message
    news:Xns95BDE40E5D02BMacCool@24.25.9.42...
    > OraceHorse:
    >
    >> Is the problem with the processor or with faulty memory?
    >
    > Here's what I would do, bump the clock back to 133Mhz and run Memtest to
    > see if it finds memory errors. If it does, replace the memory; if it locks
    > up, try it at 100Mhz. If it still locks up, then it might be the
    > processor.
    >
    > I wouldn't spend much money replacing components. For what you'll spend
    > troubleshooting you could assemble or buy a low cost new system.
    > --
    > Mac Cool

    Thanks for the response. You're quite right about the cost of
    troubleshooting.
    Still it would be satisfying to find out the problem.
    Here's some more info.
    It has 2 hard drives with 2 operating systems on each. Windows 98 and
    Windows XP and both are unstable with blue screen crashes and restarts so
    its definitely a hardware problem.

    When it was crashing frequently I ran Memtest86 and after a few seconds it
    reported around 5000 errors!
    I restarted the test and the same thing happened - 5000 errors reported
    pretty much immediately. Restarted memtest again and let it ran for hours
    with no errors!!!
    I then stopped it, booted to Windows and ran Prime 95 and it ran okay for 3
    hours until I stopped it. So the failure is intermittent. Am I right in
    thinking the memory is probably ok. If it was that badly damaged the some
    errors would show up all the time. Memtest say that if there are 1000's of
    errors this may be caused by the motherboard/processor.

    The instability in intermittent. It can go for hours being stressed with
    nothing going wrong. Then it keeps crashing after a few mins and becomes
    unusable. When this happens memtest86 shows thousands of errors after a few
    seconds.!
    This is strange
  3. Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

    OraceHorse:
    > When it was crashing frequently I ran Memtest86 and after a few
    > seconds it reported around 5000 errors!
    > I restarted the test and the same thing happened - 5000 errors
    > reported pretty much immediately. Restarted memtest again and let it
    > ran for hours with no errors!!!
    > I then stopped it, booted to Windows and ran Prime 95 and it ran okay
    > for 3 hours until I stopped it. So the failure is intermittent. Am I
    > right in thinking the memory is probably ok. If it was that badly
    > damaged the some errors would show up all the time. Memtest say that
    > if there are 1000's of errors this may be caused by the
    > motherboard/processor.

    Every bad memory stick I've had caused intermittent errors.

    > The instability in intermittent. It can go for hours being stressed
    > with nothing going wrong. Then it keeps crashing after a few mins and
    > becomes unusable. When this happens memtest86 shows thousands of
    > errors after a few seconds.!
    > This is strange

    Here's my opinion, just my opinion... the person who sold you this setup
    probably had the same problem and couldn't figure it out either. A new
    stick of memory will cost ~$30, a new CPU will cost ~$30, a new
    motherboard will cost ~$30. How much is it worth to fix?

    This may be of some help:
    http://arstechnica.com/guides/tweaks/troubleshooting.ars
    --
    Mac Cool
  4. Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

    Almost certainly just bad ram IMO.


    "Mac Cool" <Mac@2cool.com> wrote in message
    news:Xns95BEEEE70CF0BMacCool@24.25.9.42...
    > OraceHorse:
    >> When it was crashing frequently I ran Memtest86 and after a few
    >> seconds it reported around 5000 errors!
    >> I restarted the test and the same thing happened - 5000 errors
    >> reported pretty much immediately. Restarted memtest again and let it
    >> ran for hours with no errors!!!
    >> I then stopped it, booted to Windows and ran Prime 95 and it ran okay
    >> for 3 hours until I stopped it. So the failure is intermittent. Am I
    >> right in thinking the memory is probably ok. If it was that badly
    >> damaged the some errors would show up all the time. Memtest say that
    >> if there are 1000's of errors this may be caused by the
    >> motherboard/processor.
    >
    > Every bad memory stick I've had caused intermittent errors.
    >
    >> The instability in intermittent. It can go for hours being stressed
    >> with nothing going wrong. Then it keeps crashing after a few mins and
    >> becomes unusable. When this happens memtest86 shows thousands of
    >> errors after a few seconds.!
    >> This is strange
    >
    > Here's my opinion, just my opinion... the person who sold you this setup
    > probably had the same problem and couldn't figure it out either. A new
    > stick of memory will cost ~$30, a new CPU will cost ~$30, a new
    > motherboard will cost ~$30. How much is it worth to fix?
    >
    > This may be of some help:
    > http://arstechnica.com/guides/tweaks/troubleshooting.ars
    > --
    > Mac Cool
Ask a new question

Read More

Homebuilt Systems