ACTUAL RAM SPEED

  • Thread starter Thread starter kandinsky63
  • Start date Start date
kandinsky63 said this on 2/5/2009 7:17 PM:
Hi

How do I determine the actual running speed of my RAM modules?

Thanks
Click to expand...

You might download and run a program like cpu-z from cpu id.
That or go to crucial and run their memory upgrade program. Both will
/ should tell you what you have in the system, memory wise and speed
etc. Actually cpu-z tells you more about your memory that I care or
understand, maybe it will mean something to you.
 
Big_Al said:
kandinsky63 said this on 2/5/2009 7:17 PM:

You might download and run a program like cpu-z from cpu id.
That or go to crucial and run their memory upgrade program. Both will
/ should tell you what you have in the system, memory wise and speed
etc. Actually cpu-z tells you more about your memory that I care or
understand, maybe it will mean something to you.
Click to expand...

http://www.cpuid.com/cpuz.php

http://www.cpuid.com/download/cpuz_149.zip (the file that you download and unzip)

There is nothing to install. Double click "cpuz.exe" and the
program will start.

On the memory tab, typically you double the value shown
for the memory clock. For example, right now, mine
shows "266.0 MHz", and yet my actual memory is DDR2-533.
So don't be alarmed if the value is off by a factor of
two. The difference is between "clock" and "double data rate",
which accounts for the factor of two.

Paul
 
i have run cpu-z - bit dont fully understand the results. Hence i am looking
for alternate apps or guidance.
 
my bios is stating the following

" DIMM1 - 512MB/166MHz (DDR333)
DIMM2 - 512MB/166MHz (DDR333)"

The CPU-z memory tab shows '166.7 MHz'. However, the SPD tab(under timings)
states '200MHz'. What does this mean?

Also dont understand 'FSB' and 'SPD' - can anyone give nme a laymans
definition

ta
 
kandinsky63 said:
my bios is stating the following

" DIMM1 - 512MB/166MHz (DDR333)
DIMM2 - 512MB/166MHz (DDR333)"

The CPU-z memory tab shows '166.7 MHz'. However, the SPD tab(under
timings) states '200MHz'. What does this mean?

Also dont understand 'FSB' and 'SPD' - can anyone give nme a laymans
definition
Click to expand...

You could look them up, as is normal when reading technical documentation.

FSB is Front Side Bus.
http://www.cheap56k.com/glossary/FSB.html
"FSB - The speed of the bus connecting the microprocessor, its chipset, and
connected main memory. In architectures where the processor interacts
directly with main memory, the definition of a singular front side bus is
less clear. In such a case you would have to specify two FSB speeds, one for
the connection to main memory and one for the connection to the processor
chipset."

SPD means Serial Presence Detect
http://en.wikipedia.org/wiki/Serial_Presence_Detect

"Serial Presence Detect (SPD) refers to a standardized way to automatically
access information about a computer memory module. It is the serial version
of Parallel Presence Detect (PPD)."

HTH
-pk
 
kandinsky63 said:
my bios is stating the following

" DIMM1 - 512MB/166MHz (DDR333)
DIMM2 - 512MB/166MHz (DDR333)"

The CPU-z memory tab shows '166.7 MHz'. However, the SPD tab(under timings)
states '200MHz'. What does this mean?

Also dont understand 'FSB' and 'SPD' - can anyone give nme a laymans
definition

ta
Click to expand...

The BIOS takes a few things into account. For example,
the motherboard may have an upper limit on how fast
it can run the RAM. The bus loading can play a part
(some BIOS use a slower clock, if all three slots of
a single channel RAM bus are filled). The RAM
modules have their upper limit and timing numbers.
The BIOS picks numbers for the RAM, such that
the specification of the slowest of the RAM
modules is satisfied. The RAM are all run at
the same settings (they are not fed individual
values, and instead all share the same settings).
And this is why you don't want to mix a fast module
with a slow module, because the slow module will
drag you down.

Your modules may be capable of running at 200MHz (DDR400),
but the BIOS may have decided to use 166MHz as its
choice for the clock. If your computer is a pre-built
unit (HP/Acer/Gateway/Toshiba/Sony), the BIOS may not
give options to make changes. If you build the
computer from parts yourself, a retail motherboard
will usually have BIOS options, so that you can
change the settings and experiment with them. Tools
like memtest86+ can be used to check for error free
test results.

Each generation of computing equipment has different
constraints. For example, I was helping someone with
a question yesterday, and this is the table of possible
values for their board. What this table basically says,
is the maximum memory speed is a function of the
FSB speed of the processor. An FSB800 processor
allows three different possible memory speeds. If
you plugged your DDR400 modules into this board,
with an FSB800 processor, then the full performance
of the memory could be used. If you owned a FSB400
processor, then the maximum memory speed is much
lower. Your module would not be used to its full
potential.

FSB800 | FSB533 | FSB400
| |
DDR400 | |
DDR333* | DDR333 |
DDR266 | DDR266 | DDR266

Definitions -

SPD - Serial Presence Detect is a tiny chip with permanent
storage inside it. It stores the timing table for
the DIMM. That is how the BIOS knows how fast the
memory module is.

FSB - Front Side Bus. This is the bus that connects the
processor to the Northbridge. Sort of like how your
neck (bus) connects your brain (CPU) to your shoulders
(Northbridge). On a few generations of processors, this
interface was 64 bits wide (and the width has nothing to
do with the instruction set size, like 32 bit - this
width is like plumbing and using a fat pipe). On an
Intel processor, this bus is "quad pumped". What that
means, is four 64 bit data words are transferred per
clock cycle. If the input clock to the CPU is 200MHz,
then the bus runs at FSB800. The 64 bit data word is
equal to 8 bytes of data. So FSB800 (800 million transfers
per second) times 8 bytes gives 6.4GB/sec. Thus, the
Front Side Bus is capable of transferring at a rate
of 6.4GB/sec. So that is your FSB.

HTH,
Paul
 
kandinsky63 said:
my bios is stating the following

" DIMM1 - 512MB/166MHz (DDR333)
DIMM2 - 512MB/166MHz (DDR333)"

The CPU-z memory tab shows '166.7 MHz'. However, the SPD tab(under
timings) states '200MHz'. What does this mean?

Also dont understand 'FSB' and 'SPD' - can anyone give nme a laymans
definition
Click to expand...

If you look in the CPU tab you will see Bus Speed. This is the
speed of the system clock. Bus Speed X 4 = FSB, which is the
front side bus speed. The CPU multiplier, times the FSB speed
equals the CPU speed. If your CPU uses speed step, the CPU
frequency shown here may be much less than the advertised
speed of the CPU. Under load the CPU will operate at its full
speed.

On the Memory tab you will see FSB:DRAM, which is the ratio
between the FSB speed and the memory clock speed. The
DRAM frequency is the result of this ratio, which in your case
is 166.7MHz. With DDR memory, the actual memory speed is
twice that value, or 333MHz for your system (DDR333).

Ignore the timings in the SPD tab. These are values programmed
into the DIMM modules which provide the motherboard with
timing settings for different memory clock speeds.
 
Paul said:
http://www.cpuid.com/cpuz.php

http://www.cpuid.com/download/cpuz_149.zip (the file that you download and unzip)

There is nothing to install. Double click "cpuz.exe" and the
program will start.

On the memory tab, typically you double the value shown
for the memory clock. For example, right now, mine
shows "266.0 MHz", and yet my actual memory is DDR2-533.
Click to expand...

That is because of the definition of DDR: DOUBLE Data Rate. There are 2
reads per read cycle hence the doubling. No, you do NOT double the
clock rate to determine the memory speed. You already know it. If all
you know is DDR-533 then you *halve* the spec to find out what is the
max speed used for the clock rate on the memory.

Read:
http://en.wikipedia.org/wiki/DDR_memory
So don't be alarmed if the value is off by a factor of
two. The difference is between "clock" and "double data rate",
which accounts for the factor of two.
Click to expand...

Yep, correct.
 
kandinsky63 said:
my bios is stating the following

" DIMM1 - 512MB/166MHz (DDR333)
DIMM2 - 512MB/166MHz (DDR333)"

The CPU-z memory tab shows '166.7 MHz'. However, the SPD tab(under timings)
states '200MHz'. What does this mean?
Click to expand...

Depends on whether you have the BIOS use the SPD settings (what the
memory reports as its validated speed specs) or the BIOS is configured
to use a selected speed set. Just because SPD settings are listed
doesn't mean that is what the BIOS is actually using. You could, after
all, be overclocking your 166MHz memory by running it at 200MHz. If you
want to use the actual specs for the device (by reading AND using the
SPD specs) then you need to configure the BIOS to use the SPD values
(i.e., select "SPD detect"). Overclocking should only be done by those
intimate with their hardware, willing to burn out parts (and possibly
have to replace other charred parts), and willing to endure prolonged
testing to determine where stability suffers when overclocking is set
too extreme.

The memory modules are *rated* for continuous operation at 166MHz.
However, your BIOS has been configured to *run* them overclocked at
200MHz. Consider if you want a stable machine at a tiny loss in
performance (usually only detectable in benchmarks and not in
applications) or if you want an unstable host with a tiny performance
gain. Unless you know, practice, and are willing to suffer overclocking
experimentation, don't do it.

Manufacturers often produce parts in one assembly line that fail testing
at high specs so they sell at lower specs. Problem is that their
assembly line may have so few failures that they don't have enough to
sell at the lower spec. Many customers expect paying lower prices for
lower spec'ed parts and manufacturers must fulfill this market's wants.
So they produce their high-spec parts but label them as low-spec parts
to sell them at a lower price. However, the SPD is programmed at the
end of the assembly process and should match on the lower-spec under
which they sell the component. Those in the know about the parts by
research or personal experience might know that these low-spec parts
have a good chance of being overclocked, so they install the low-spec
parts (at a cheaper price) and then overclock them. In fact, you have
to be careful when buying, for example, a video card because many will
sell at a higher price but are actually just overclocked products. BFG
is one such video card brand that likes to sell overclocked video cards.
Be aware of any part that mentions "OC" in their product description.
They're overclocked and maybe you don't want those. A stable host is
far more valuable than one that achieve 2% to 5% performance gain which
is usually only measurable in benchmarks and not under real use.
 
thanks for all your contributions - however, i am still struggling to
understand the tech speak.
More info:

I have the following ;

1. Asrock P4VM800 DDR FSB 800/533 mobo
2. 2x 512MB DDR (PC3200) 400MHz
3. Intel Celeron 3.06GHz 533 cpu

when I went into the BIOS settings, I found that the RAM was being recorded
as

" DIMM1 - 512MB/166MHz (DDR333)
DIMM2 - 512MB/166MHz (DDR333)"

what i dont understand is why the BIOS is stating the RAM modules to be
DDR333 with a frequency of 166MHz and NOT the expected DDR400 with a
frequency of 200MHz ?

Or am i missing something?

Simple explanations please :-)
 
kandinsky63 said:
thanks for all your contributions - however, i am still struggling to
understand the tech speak.
More info:

I have the following ;

1. Asrock P4VM800 DDR FSB 800/533 mobo
2. 2x 512MB DDR (PC3200) 400MHz
3. Intel Celeron 3.06GHz 533 cpu

when I went into the BIOS settings, I found that the RAM was being
recorded as

" DIMM1 - 512MB/166MHz (DDR333)
DIMM2 - 512MB/166MHz (DDR333)"

what i dont understand is why the BIOS is stating the RAM modules to be
DDR333 with a frequency of 166MHz and NOT the expected DDR400 with a
frequency of 200MHz ?

Or am i missing something?

Simple explanations please :-)
Click to expand...
Your FSB is 533MHz, so you motherboard is being conservative
and using the DDR333 timing for a 3:1 FSB:DRAM ratio. If you
had an 800MHz FSB CPU, it would most likely use a 2.1 ratio and
a 200MHz memory clock speed for a 400MHz DDR speed. You
should be able to set the proper memory speed in BIOS.
 
Paul said:
kandinsky63 said:
thanks for all your contributions - however, i am still struggling to
understand the tech speak.
More info:

I have the following ;

1. Asrock P4VM800 DDR FSB 800/533 mobo
2. 2x 512MB DDR (PC3200) 400MHz
3. Intel Celeron 3.06GHz 533 cpu

when I went into the BIOS settings, I found that the RAM was being
recorded as

" DIMM1 - 512MB/166MHz (DDR333)
DIMM2 - 512MB/166MHz (DDR333)"

what i dont understand is why the BIOS is stating the RAM modules to be
DDR333 with a frequency of 166MHz and NOT the expected DDR400 with a
frequency of 200MHz ?

Or am i missing something?

Simple explanations please :-)
Click to expand...

http://www.asrock.com/mb/overview.asp?Model=P4VM800&s=478

http://download.asrock.com/manual/P4VM800.pdf

Memory:
2 DDR DIMM Slots

1 DDR DIMM Slot Supports PC3200 (DDR400), Max. 1GB

2 DDR DIMM Slots Supports PC2700 (DDR333) / PC2100 (DDR266), Max. 2GB

That says, when there is the bus loading of two installed
DIMMs, the motherboard reduces the clock to 166MHz, so
there won't be memory errors.

If you wish, you can attempt to adjust the memory speed
in the BIOS. See PDF page 24, where the DRAM frequency
setting is shown. By leaving the other timing settings
at "Auto", the BIOS will work out the correct values for
the new DDR400 setting. For example

DRAM Frequency [200MHz] <--- The new, experimental value
Flexibility Option [Disabled]
DRAM CAS# Latency [Auto] <--- BIOS works out the correct CAS value
DRAM Command Rate [2T] <--- This setting reduces overall
performance
but improves stability under heavy
load.
With two sticks, I'd leave this at 2T.
If you try 1T, it may crash instantly
at DDR400.

DDR333 (166MHz memory clock), is Asrock's best guess at
the maximum speed at which two DIMMs will be stable.
You, as the owner can experiment with that, and see
if more is possible. To test the memory, you should
prepare a test floppy or test CD, using a program
like this. *Don't* attempt to immediately boot into
Windows, after adjusting memory - if the error rate
is extremely high on the memory, your Windows installation
can be corrupted. Use this tool to boot the computer, right
after the memory setting has been changed. Allow at least
two complete "passes", before pressing the escape key
and booting into Windows. If you spot any errors,
then re-enter the BIOS and change the setting back.
Then, boot memtest86+ again, and test that even
the DDR333 setting is stable. Don't try booting
until you have some small amount of evidence that
the memory is fine.

http://www.memtest.org/

Once you're in Windows, run this test for up to four hours.
No errors are allowed with this one either. I'm running
this in the background right now, testing a new 2GB stick of
memory. (click the "stress test" option. Then use Options:Torture_Test
in the menu. Later, use Test:Stop followed by Test:Exit, to
completely stop the program.)

http://www.mersenne.org/ftp_root/gimps/p95v258.zip

Paul
Click to expand...

So the motherboard won't handle two DIMMs at DDR400. I
never thought of that. I could see it when going from 2 to
4 DIMMs, but on going from 1 to 2, that's a pretty weak memory
bus.
 
Ian said:
So the motherboard won't handle two DIMMs at DDR400. I
never thought of that. I could see it when going from 2 to
4 DIMMs, but on going from 1 to 2, that's a pretty weak memory
bus.
Click to expand...

Every generation and manufacturer has had their surprises.
It's hard to keep track of them all. For example,
I still don't have a good road map for DDR2 and
DDR3. If a person asked a question about those, I
pretty well have to look up every board.

Paul
 
Hi

I have spoken with Asrock and they suggest just setting the memory frequency
to 200MHz and the rest of BIOS to default. They went on to say that if this
change from 166MHz to 200MHz causes system instability the change the
memory frequency back to the AUTO default of 166MHz.

I have got memtest84+ and will run it overnight on the new 200MHz setting.
Will let u know what happens.
 
the zip folder does not appear to contain a .exe file. It does contain
MemLatency.aps but no MemLatency.exe.
??
 
i set the DRAM frequecy in BIOS to 200MHz . However, the CPU-Z (CPUID) app
still show, under the Memory tab, 166.7MHz. Dont understand why its
showing this value and not 200MHz???

Any advice?
 
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