When a poster can say why he made a statement, only then do
we have a post of merit. Unless one can tell us what tests
the hardware tester and software tester perform, only then do
we have minimal information on the reliability or value of
either tester. Statements made without significant reasons
why akin to wasting bandwidth.
I was writing memory tests long before PCs even existed.
Many of the traditional tests include marching ones and
marching zeros, full one and full zeroes, the checkerboard
test, and other 'standard' tests. In one case, the board has
passed every marching zero test and every marching one test -
then failed a 'next to last' test. Why did that memory
location pass every test previously? Memory location only
failed when enough adjacent memory locations were opposite
logic state long enough to leak charges. Even the
manufacturer tests would not detect this memory failure. Not
only did I detect a failure, BUT, I also must know why.
Without also knowing why, then I would not have sufficient
knowledge to post.
Meantime, defined was how to make even a cheap tester
superior to more expensive testers. Heat memory with a
hairdryer on highest heat. This from someone who was writing
computer memory tests even for core memory. When did you work
on core memory computers? This from someone who would find
defective memory after standard test said memory was OK - but
computer still crashed. I was writing memory tests probably
before most lurkers even existed. I cannot say enough about
testing under elevated temperature - which is a delightful and
normal temperature to functioning memory.
Again, once a poster demonstrates a grasp of how memory
fails, how the many testers actually work, and provide the
"why" details, only then are we ready to enhance our
knowledge. Currently almost nothing has been posted here
about a good or inferior tester .... because reasons why and
underlying grasp of the concepts are not included in that
post.
The author of that cited review (realworldtech.com) feels
that 'poor quality or slow memory' caused problems. Nice.
But it tells us nothing. Define 'poor quality'? Define
'slow'? He makes no attempt to even discuss basics of why
memories fail - what symptoms cause memory failure. I suspect
he may be just inventing these definitions because he did not
actually learn what was defective in each memory.
To provide useful information, the author must have a grasp
of basic concepts - the underlying theory - AND support his
theories with experimental evidence. Both conditions are
necessary to understand - to know. For example, how long
after the memory address is provided does memory then provide
data from that location? Specific numbers exist for this
parameter. How long can memory hold data before requiring a
refresh? Again a parameter that memory testers would test. Is
voltage driver for that data output sufficient to drive a
fully loaded bus? Not hard to test for and could be listed as
one of the many tests for a good hardware tester.
So many parameters to test. So many ways a memory can
fail. So few of these parameters are tested for let alone
even mentioned. Author makes no effort to define each
possible failure condition let alone suggest he even knows why
memories fail.
IOW his tests provides nothing more than speculation based
upon random defective memories. Defects that we don't even
know why they are defective.
The problem. This citation that is not based upon even
minimally acceptable technical facts is offered as the best
proof of good memory testers. Unfortunately among many
technically knowledgeable computer professionals, that
woefully inadequate article constitutes a proof - rather than
nothing more than outright speculation.
Meanwhile, one condition that tends to aggravate many
marginal conditions into a hard failure mode - heat. This is
also why so many naive computer assemblers instead recommend
more fans for the system - to cure the symptoms rather than a
hardware problem. Heat is a most effective diagnostic tool
for electronics - especially memory.
D & B wrote:
> How much does a good hardware memory tester cost, and do most computer
> shops with hardware testers have the good ones? I've seen some selling
> for $500 US, and one store said that theirs cost $700.
>
> If software testers are useless, why have they found defects in some of
> the modules I've bought (only those with no-name chips, not those with
> chip makers' part numbers on them) and have done so consistently with
> each pass?
>
> Also how do you explain this:
> http://www.realworldtech.com/page.cf...WT052001232443 and this:
> http://www.realworldtech.com/page.cf...WT120901222920 , where some
> software testers did as well as the hardware testers from Ultra-X?