relationship memory speed & voltage ???

[student]

Upped memory to 4 gig BUT problem is that memory is running at
400 mhz & 1.8 volts. I had to switch the memory using the new
OCZ to bank 1 & the old Crucial to bank 2 before the computer would
boot up.

The OCZ is rated at 800 mhz @ 2.1 volts; the Crucial is 800 mhz @ 1.8 v.

I had thought that the "higher volts" would equate to higher speed but
looking at some memories, I find that that is not always the case. I don't
know how much higher I can boost the memory voltage before messing
the Crucial (couldn't find anything about a "safe max").

The machine isn't for gaming except for some pinball games & will be doing
some video editing ( only the ""bare minimum"); so far running at 400 mhz
doesn't look to be much slower than that of 2 gig @ 800 mhz.

So, any "rule of thumb" for memory speed, voltage, cas matching?

 

[peter]

DDR2 memory?? in DDR2 400=800
What exactly does your mobo Bios say??
peter

 

[John Doe]

Upped memory to 4 gig

I think Windows XP can handle up to 3 GB.

The OCZ is rated at 800 mhz @ 2.1 volts; the Crucial is 800 mhz @
1.8 v.

I had thought that the "higher volts" would equate to higher speed

The voltage a circuit requires depends on the circuit technology. I
think smaller technology requires less voltage because there's less
distance to push current around. But that's not very relevant.

So, any "rule of thumb" for memory speed, voltage, cas matching?

Faster memory of the same category might be able to run at a lower
speed, so it can be used with slower memory of the same category.

Voltage needs to be the same. Supply voltages have tolerances, but
most of us shouldn't be messing with that.

I'm not sure about CAS. It's probably similar to speed, although
there might be lower limits. Matched probably would be best.

Memory is tricky stuff. Good luck and have fun.

 

[Paul]

Upped memory to 4 gig BUT problem is that memory is running at
400 mhz & 1.8 volts. I had to switch the memory using the new
OCZ to bank 1 & the old Crucial to bank 2 before the computer would
boot up.

The OCZ is rated at 800 mhz @ 2.1 volts; the Crucial is 800 mhz @ 1.8 v.

I had thought that the "higher volts" would equate to higher speed but
looking at some memories, I find that that is not always the case. I don't
know how much higher I can boost the memory voltage before messing
the Crucial (couldn't find anything about a "safe max").

The machine isn't for gaming except for some pinball games & will be doing
some video editing ( only the ""bare minimum"); so far running at 400 mhz
doesn't look to be much slower than that of 2 gig @ 800 mhz.

So, any "rule of thumb" for memory speed, voltage, cas matching?

For a Crucial DIMM, the chips on it are likely to be from Micron.
Micron owns Crucial.

This is a datasheet for a DDR2-800 CAS5 chip. Page 82 lists
"Absolute Max" as 2.3V. So if you run all your DIMMs at 2.1V,
then presumably they are all safe.

http://download.micron.com/pdf/datasheets/dram/ddr2/512MbDDR2.pdf

If I look at a page full of Crucial memory solutions, the Ballistix
stuff is rated 2.2V and the regular memory is rated 1.8V. (And
1.8V is the industry standard voltage for DDR.) So basically,
for their overclocking products, they are listing 2.2V as the max.
While that Micron datasheet suggests the "Absolute Max" is 2.3V.

http://www.crucial.com/store/listparts.aspx?model=P5K

The purpose of voltage, is to enhance performance. It is the
equivalent of something an overclocker would do, to use more
voltage than the industry standard. Put in other words, a
memory chip will run up to speed "X" at 1.8V and will run up to
speed "Y" at 2.2V. When the chip is manufactured, it is initially
tested at 1.8V and verified to run at "X". A part number is stamped
on the chip, and the speed stated there, should have corresponded
to 1.8V operation. Now, if someone wants to make "overclocker RAM",
they may increase the voltage a bit. If the chip has a rated
Absolute Max of 2.3, then they could make products at 1.9, 2.0,
2.1, 2.2, but perhaps if they were smart, they wouldn't try to
rest the RAM right on the line at 2.3. They test the RAM to
see how fast it runs. Corsair, in fact, uses computer motherboards
as a test vehicle, to test their RAM. So they don't use factory
style testers to do it.

So when you see a RAM rated at 2.0V, it means they found in their
testing, that it would run a little faster, at speed "Y", if they
applied 2.0V to it. You'd have to check with each company that
makes the raw chips, to see whether they can stand 2.3V or some
other value. My assumption in the case of Crucial, is that Micron
chips are used, but there could be different generations of chips
that have different limitations.

During daylight hours, Crucial has a "Live Chat" feature on their
web page, and maybe you could chat with one of their reps, and
give them the part number, and get them to verify the max value
(of their 1.8V stuff) for you. The max for the 1.8V stuff should
be 2.2V, just like their premium stuff.

I noticed in one thread, people applying more than the
absolute maximum value, to some Micron D9, so I guess
they can take more than that. Too much juice, and they're
bound to get hot.

http://www.xtremesystems.org/forums/archive/index.php/t-101762.html

Paul

 

[student]

For a Crucial DIMM, the chips on it are likely to be from Micron.
Micron owns Crucial.

This is a datasheet for a DDR2-800 CAS5 chip. Page 82 lists
"Absolute Max" as 2.3V. So if you run all your DIMMs at 2.1V,
then presumably they are all safe.

http://download.micron.com/pdf/datasheets/dram/ddr2/512MbDDR2.pdf

If I look at a page full of Crucial memory solutions, the Ballistix
stuff is rated 2.2V and the regular memory is rated 1.8V. (And
1.8V is the industry standard voltage for DDR.) So basically,
for their overclocking products, they are listing 2.2V as the max.
While that Micron datasheet suggests the "Absolute Max" is 2.3V.

http://www.crucial.com/store/listparts.aspx?model=P5K

The purpose of voltage, is to enhance performance. It is the
equivalent of something an overclocker would do, to use more
voltage than the industry standard. Put in other words, a
memory chip will run up to speed "X" at 1.8V and will run up to
speed "Y" at 2.2V. When the chip is manufactured, it is initially
tested at 1.8V and verified to run at "X". A part number is stamped
on the chip, and the speed stated there, should have corresponded
to 1.8V operation. Now, if someone wants to make "overclocker RAM",
they may increase the voltage a bit. If the chip has a rated
Absolute Max of 2.3, then they could make products at 1.9, 2.0,
2.1, 2.2, but perhaps if they were smart, they wouldn't try to
rest the RAM right on the line at 2.3. They test the RAM to
see how fast it runs. Corsair, in fact, uses computer motherboards
as a test vehicle, to test their RAM. So they don't use factory
style testers to do it.

So when you see a RAM rated at 2.0V, it means they found in their
testing, that it would run a little faster, at speed "Y", if they
applied 2.0V to it. You'd have to check with each company that
makes the raw chips, to see whether they can stand 2.3V or some
other value. My assumption in the case of Crucial, is that Micron
chips are used, but there could be different generations of chips
that have different limitations.

During daylight hours, Crucial has a "Live Chat" feature on their
web page, and maybe you could chat with one of their reps, and
give them the part number, and get them to verify the max value
(of their 1.8V stuff) for you. The max for the 1.8V stuff should
be 2.2V, just like their premium stuff.

I noticed in one thread, people applying more than the
absolute maximum value, to some Micron D9, so I guess
they can take more than that. Too much juice, and they're
bound to get hot.

http://www.xtremesystems.org/forums/archive/index.php/t-101762.html

Paul

Thanks again for the info; have saved the Crucial pdf as well.

I found I had a problem with EMI on the sound but was able to disable the
sound out from my external speaker by setting the bios cpu/ldt to
"down spread" mode from "center spread" when running at 4 gig. Found
that a "FAQ" somewhere that the 400 mhz cpuz displays is for real memory
whereas the 800 mhz designation is a "nominal" memory speed for 2 cards
in DDR2 mode..

The curious thing is that cpuz shows the ram voltage as 1.8 v for all 4 slots
while MSI's Core Dual Center shows 2.05 volts; no idea what is the real thing
but as it is below the 2.3 v for Crucial & the rated 2.1 for OCZ, I'm ok as
the bios settings are on auto.

I guess the cpuz memory page showing the timing as 5-6-6-18 is the
lesser being used from the spd page which showed the OCZ as 5-5-5-15
& the Crucial as 5-6-6-18 which is different from the spec.

Oh well, the system is working well now & will install linux x64 next weekend
as a dual boot to see how that goes....

 

[John Doe]

I noticed in one thread, people applying more than the absolute
maximum value, to some Micron D9, so I guess they can take more
than that. Too much juice, and they're bound to get hot.

And produce more errors.