Questions about DDR RAM

[Igor]

I'm planning to add some memory to a PC. The motherboard supports "DDR up
to 333 MHz (enhanced) memory bus."

333 MHz (PC2700) or slower DDR SDRAM isn't easy to find on today's market,
and when you do find it, it's considerably more expensive than the DDR
which runs at 400 MHz (PC3200). What would happen if I bought 400 MHz DDR
RAM and installed it in a motherboard which only supports speeds up to 333
MHz (PC2700)? Would it work? If it did work, would it work as well as the
slower PC2700 RAM?

I've gotten conflicting answers to this question. Two computer stores told
me that it wouldn't work. Another store and a book I consulted said it
would.

I'd also like some opinions on which brand of RAM I should get. Kingston
and Samsung are ubiquitous where I live, so the choice comes down to one
of those. Both brands are about the same price, with the Samsung being
marginally cheaper.

Finally, would a 128 MB stick of 266 MHz DDR RAM be able to run in the
same computer as, say, a 512 MB stick of 400 MHz DDR RAM? If so, would
using both at the same time degrade the performance of the faster RAM?

 

[kony]

I'm planning to add some memory to a PC. The motherboard supports "DDR up
to 333 MHz (enhanced) memory bus."

333 MHz (PC2700) or slower DDR SDRAM isn't easy to find on today's market,
and when you do find it, it's considerably more expensive than the DDR
which runs at 400 MHz (PC3200). What would happen if I bought 400 MHz DDR
RAM and installed it in a motherboard which only supports speeds up to 333
MHz (PC2700)? Would it work? If it did work, would it work as well as the
slower PC2700 RAM?

Yes it'll work and do so as well/fast as PC2700, providing
it has timings spec'd at least as (Low) fast as the PC2700
module had. This is not a large difference in performance
though so a random suggestion would be to get a CAS2.5 @ 2.5
or 2.6V spec'd part.

I've gotten conflicting answers to this question. Two computer stores told
me that it wouldn't work. Another store and a book I consulted said it
would.

Avoid those two computer stores from now on when seeking
advice, or at least the particular techs you spoke with as
PC3200 is always backwards compatible. It's the same memory
only the maxium speed the PC3200 is guaranteed to be able to
run stabily is higher, and the prom on the module is
programmed with timings to validate this if/when a
motherboard checks to see what the memory can do.

I'd also like some opinions on which brand of RAM I should get. Kingston
and Samsung are ubiquitous where I live, so the choice comes down to one
of those. Both brands are about the same price, with the Samsung being
marginally cheaper.

Which country do you reside in? Often buying online is
cheaper unless there's a particularly good sale or rebate
ongoing. Kingston's valueram tends to be lower spec, many
other name brand modules are better or cheaper for the same
specifications.

Finally, would a 128 MB stick of 266 MHz DDR RAM be able to run in the
same computer as, say, a 512 MB stick of 400 MHz DDR RAM? If so, would
using both at the same time degrade the performance of the faster RAM?

The two could run in single channel mode, which would be the
mode it was in currently. Some motherboard chipsets can run
dual channel mode for a performance increase (which varies
from very little to a fair amount) and some of these require
two of same size and compatible timings, modules. Some only
require two modules with compatible timings but need not be
the same size (would then support dual channel mode only up
to the amount of memory of the smallest module total on one
channel, times 2). nForce 2 is an example of such a chipset
that can do this, though unless using integrated video the
performance gain from dual channel mode is minimal.

 

[CBFalconer]

I'm planning to add some memory to a PC. The motherboard supports
"DDR up to 333 MHz (enhanced) memory bus."

333 MHz (PC2700) or slower DDR SDRAM isn't easy to find on today's
market, and when you do find it, it's considerably more expensive
than the DDR which runs at 400 MHz (PC3200). What would happen if
I bought 400 MHz DDR RAM and installed it in a motherboard which
only supports speeds up to 333 MHz (PC2700)? Would it work? If it
did work, would it work as well as the slower PC2700 RAM?

I've gotten conflicting answers to this question. Two computer
stores told me that it wouldn't work. Another store and a book I
consulted said it would.

The faster stuff is just fine. The stores want to unload their old
stock, or are completely lacking in knowledge. Take your pick.
But, if the MB can handle it, ensure you get ECC capable memory.

 

[jameshanley39]

I'm planning to add some memory to a PC. The motherboard supports "DDR up
to 333 MHz (enhanced) memory bus."

333 MHz (PC2700) or slower DDR SDRAM isn't easy to find on today's market,
and when you do find it, it's considerably more expensive than the DDR
which runs at 400 MHz (PC3200). What would happen if I bought 400 MHz DDR
RAM and installed it in a motherboard which only supports speeds up to 333
MHz (PC2700)? Would it work? If it did work, would it work as well as the
slower PC2700 RAM?

I've gotten conflicting answers to this question. Two computer stores told
me that it wouldn't work. Another store and a book I consulted said it
would.

I don't understand this. You went into stores asking?!!!! You
consulted books?!!!

This is such an obvious question to ask. Lots of people have asked it
on usenet.

Didn't you think to search usenet?

you're concerned about price and asking on the internet, and it didn't
occur, or you lacked the confidence, to buy on the internet?!

I'd also like some opinions on which brand of RAM I should get. Kingston
and Samsung are ubiquitous where I live, so the choice comes down to one
of those. Both brands are about the same price, with the Samsung being
marginally cheaper.

GOOD MAKES OF RAM
this is an obvious search. You can read books but you can't use
google?!!!!
Kingston and Crucial are good makes. I seem to recall somebody here
saying one wasn't so good, but they work for most people. Don't get a
bad or unknown or unlabelled make / unbranded ram.

Finally, would a 128 MB stick of 266 MHz DDR RAM be able to run in the
same computer as, say, a 512 MB stick of 400 MHz DDR RAM?

you mean at the same time?
i'd try it. it's unlikely that the mbrd wouldn't like it, and even
then, it's unlikely that it'd smoke out.

If so, would
using both at the same time degrade the performance of the faster RAM?

I vaguely recall that they'd run at the slower speed. .

(Note: I'm using a bogus reply-to address to avoid spam, so please don't
reply by email.)

You know about spam, so learn how to search usenet. Your behaviour
doesn't seem logical. What kind of justification do you have?!

 

[larry moe 'n curly]

I'm planning to add some memory to a PC. The motherboard supports "DDR up
to 333 MHz (enhanced) memory bus."

333 MHz (PC2700) or slower DDR SDRAM isn't easy to find on today's market,
and when you do find it, it's considerably more expensive than the DDR
which runs at 400 MHz (PC3200). What would happen if I bought 400 MHz DDR
RAM and installed it in a motherboard which only supports speeds up to 333
MHz (PC2700)? Would it work? If it did work, would it work as well as the
slower PC2700 RAM?

The only time a good PC3200 module didn't work with one of my slower
mobos was when I set the mobo's BIOS to use the "safe" default
timings. That caused an ECS K7S5A Pro (max memory speed: 266 MHz) to
not boot and show only a completely blank screen.

I'd also like some opinions on which brand of RAM I should get. Kingston
and Samsung are ubiquitous where I live, so the choice comes down to one
of those. Both brands are about the same price, with the Samsung being
marginally cheaper.

I'd get Samsung because Samsung is a real RAM chip manufacturer while
Kingston just buys chips or silicon wafers from other companies and
doesn't seem to test them very thoroughly. About 20-30% of the
Kingstons I've tried were troublesome, with a whopping 8 out of 11-12
PC3200 512MB Kingston ValueRAMs failing. OTOH all 5 PC3200 512MB PNY
modules worked fine, even when overclocked (I don't normally
overclock). I strongly recommend testing each module overnight with
both MemTest86 AND Gold Memory.

Finally, would a 128 MB stick of 266 MHz DDR RAM be able to run in the
same computer as, say, a 512 MB stick of 400 MHz DDR RAM?

I was able to run a 256MB PC2100 and 512MB PC3200 together in a mobo
that supported 400 MHz. I don't know what happened to the timings of
the faster RAM.

 

[Igor]

I don't understand this. You went into stores asking?!!!! You
consulted books?!!!

This is such an obvious question to ask. Lots of people have asked it
on usenet.

Didn't you think to search usenet?

you're concerned about price and asking on the internet, and it didn't
occur, or you lacked the confidence, to buy on the internet?!


GOOD MAKES OF RAM
this is an obvious search. You can read books but you can't use
google?!!!!
Kingston and Crucial are good makes. I seem to recall somebody here
saying one wasn't so good, but they work for most people. Don't get a
bad or unknown or unlabelled make / unbranded ram.




you mean at the same time?
i'd try it. it's unlikely that the mbrd wouldn't like it, and even
then, it's unlikely that it'd smoke out.


I vaguely recall that they'd run at the slower speed. .


You know about spam, so learn how to search usenet. Your behaviour
doesn't seem logical. What kind of justification do you have?!

If you don't have anything intelligent to say, it's better that you don't
say anything at all.

 

[Igor]

Which country do you reside in? Often buying online is
cheaper unless there's a particularly good sale or rebate
ongoing. Kingston's valueram tends to be lower spec, many
other name brand modules are better or cheaper for the same
specifications.

I live in Canada. Which Internet-based retailers would you recommend?

The more popular mailorder places in the U.S. won't ship to Canada, most
likely due to import/export restrictions.

I don't like eBay for a variety of reasons and will not do business
through them.

I looked at the prices at tigerdirect.ca and didn't find them to be
appreciably better than the computer stores in my neighbourhood (a $3 or
$4 difference, not counting shipping). Frankly, for such small potential
savings, I prefer the convenience of buying locally.

 

[Igor]

But, if the MB can handle it, ensure you get ECC capable memory.

My motherboard's manual doesn't say anything about supporting ECC, so I'll
assume that it doesn't.

However, I plan on putting together a PC from scratch in the near future,
so perhaps ECC support is something I should be looking for in a
motherboard.

In a nutshell, why is ECC capable memory more desirable?

 

[Igor]

The only time a good PC3200 module didn't work with one of my slower
mobos was when I set the mobo's BIOS to use the "safe" default
timings. That caused an ECS K7S5A Pro (max memory speed: 266 MHz) to
not boot and show only a completely blank screen.

That's good to know, as the motherboard I'm dealing with is also an ECS.

I'd get Samsung because Samsung is a real RAM chip manufacturer while
Kingston just buys chips or silicon wafers from other companies and
doesn't seem to test them very thoroughly. About 20-30% of the
Kingstons I've tried were troublesome, with a whopping 8 out of 11-12
PC3200 512MB Kingston ValueRAMs failing. OTOH all 5 PC3200 512MB PNY
modules worked fine, even when overclocked (I don't normally
overclock). I strongly recommend testing each module overnight with
both MemTest86 AND Gold Memory.

Thanks for your opinion, and even better, for backing it up with something
more than "I'm using brand X because that's what everyone says is the
best."

I'm not familiar with the programs you mention but I will do a search for
them.

I'll follow your recommendation, and make sure I can return the memory if
it fails.

I was able to run a 256MB PC2100 and 512MB PC3200 together in a mobo
that supported 400 MHz. I don't know what happened to the timings of
the faster RAM.

I guess I'll just have to try it and see

 

[~misfit~]

Somewhere on the interweb "(e-mail address removed)" typed:

I vaguely recall that they'd run at the slower speed. .

Your vague recollections are of little use to someone asking for facts.

You know about spam, so learn how to search usenet. Your behaviour
doesn't seem logical. What kind of justification do you have?!

And yours seems agressive and antagonistic. What's your justification? On
second thoughts, just go away.

 

[~misfit~]

Somewhere on the interweb "Igor" typed:

My motherboard's manual doesn't say anything about supporting ECC, so
I'll assume that it doesn't.

However, I plan on putting together a PC from scratch in the near
future, so perhaps ECC support is something I should be looking for
in a motherboard.

In a nutshell, why is ECC capable memory more desirable?

http://en.wikipedia.org/wiki/ECC_memory#Error-correcting_memory

Not the best description but it will suffice.

In a nutshell, to quote from the Wiki page:

"ECC memory provides greater data accuracy and system uptime by protecting
against soft errors in computer memory."

However, it comes at a price. It depends on what you're using your PC for
really. I have two PCs with ECC RAM and the rest without. IMO for
non-mission-critical machines its' not really needed.

 

[chrisv]

My motherboard's manual doesn't say anything about supporting ECC, so I'll
assume that it doesn't.

However, I plan on putting together a PC from scratch in the near future,
so perhaps ECC support is something I should be looking for in a
motherboard.

In a nutshell, why is ECC capable memory more desirable?

Most people don't care, and most mobo's won't support it.

 

[Mike Walsh]

I'm planning to add some memory to a PC. The motherboard supports "DDR up
to 333 MHz (enhanced) memory bus."

333 Mhz is the maximum speed of the memory bus, not the maximum speed of the memory that will work.

333 MHz (PC2700) or slower DDR SDRAM isn't easy to find on today's market,
and when you do find it, it's considerably more expensive than the DDR
which runs at 400 MHz (PC3200). What would happen if I bought 400 MHz DDR
RAM and installed it in a motherboard which only supports speeds up to 333
MHz (PC2700)? Would it work? If it did work, would it work as well as the
slower PC2700 RAM?

You can always use memory rated for a higher speed than the memory bus if it is the correct type, e.g. don't try to use DDR2 in place of DDR memory.

I've gotten conflicting answers to this question. Two computer stores told
me that it wouldn't work. Another store and a book I consulted said it
would.

Never ask a salesman a technical question.

I'd also like some opinions on which brand of RAM I should get. Kingston
and Samsung are ubiquitous where I live, so the choice comes down to one
of those. Both brands are about the same price, with the Samsung being
marginally cheaper.

I have had good results with Kingston, never used Samsung.

Finally, would a 128 MB stick of 266 MHz DDR RAM be able to run in the
same computer as, say, a 512 MB stick of 400 MHz DDR RAM? If so, would
using both at the same time degrade the performance of the faster RAM?

Both DIMMs would run at 266 Mhz.

 

[Andrew]

However, I plan on putting together a PC from scratch in the near future,
so perhaps ECC support is something I should be looking for in a
motherboard.

In a nutshell, why is ECC capable memory more desirable?

It has additional bits used to store checksum information so that
errors can be detected and simple ones corrected. In short, it's a
reliability thing. Without knowing much about your set up, it's
impossible to be sure but at three or four times the cost of normal
RAM I doubt it will be a cost-effective way of improving
reliability. If you want to do that on most systems, you're better
off spending the money on things like fitting a UPS and RAID storage -
these cover much less reliable elements of the system.

Memory is fairly reliable provided you aren't recklessly overclocking
things so I'd consider ECC inappropriate on all but the most mission-
critical systems. Unless you are talking about a machine already
fitted out with a UPS, hot-swappable RAID, redundant power supplies
and preferably an secure, climate controlled machine room to put it
all in there are more important risk factors to consider.

 

[Igor]

It has additional bits used to store checksum information so that
errors can be detected and simple ones corrected. In short, it's a
reliability thing. Without knowing much about your set up, it's
impossible to be sure but at three or four times the cost of normal
RAM I doubt it will be a cost-effective way of improving
reliability. If you want to do that on most systems, you're better
off spending the money on things like fitting a UPS and RAID storage -
these cover much less reliable elements of the system.

Memory is fairly reliable provided you aren't recklessly overclocking
things so I'd consider ECC inappropriate on all but the most mission-
critical systems. <snip>

I don't plan on overclocking (recklessly or otherwise), so I'd say you're
right. I've been using a computer I had custom built a few years ago as a
DAW (digital audio workstation). All it has is a stick of cheap, non-ECC
RAM, and I've never had any problems.

If I had unlimited funds and I was trying to build the ultimate computer,
I'd spring for ECC, but in the real world, budgets matter, and I've been
getting fine without it so far.

 

[kony]

Memory is fairly reliable provided you aren't recklessly overclocking
things so I'd consider ECC inappropriate on all but the most mission-
critical systems. Unless you are talking about a machine already
fitted out with a UPS, hot-swappable RAID, redundant power supplies
and preferably an secure, climate controlled machine room to put it
all in there are more important risk factors to consider.

None of those risk factors change whether the results of
data calculations are important.

I would say ECC is appropriate for any even slightly
critical application, not just "the most mission critical".
You spend a few bucks more for better PSU, case, processor,
etc, why not the memory? Your data links usually have error
correction, as does a hard drive internally, as does the
processor cache, but main memory is a weak link in data
integrity.

 

[Yousuf Khan]

I'm planning to add some memory to a PC. The motherboard supports "DDR
up to 333 MHz (enhanced) memory bus."

333 MHz (PC2700) or slower DDR SDRAM isn't easy to find on today's
market, and when you do find it, it's considerably more expensive than
the DDR which runs at 400 MHz (PC3200). What would happen if I bought
400 MHz DDR RAM and installed it in a motherboard which only supports
speeds up to 333 MHz (PC2700)? Would it work? If it did work, would it
work as well as the slower PC2700 RAM?

I've gotten conflicting answers to this question. Two computer stores
told me that it wouldn't work. Another store and a book I consulted said
it would.

I'll bet the boys in the first two shops were confused between DDR vs.
DDR2 DRAM. The type of memory you're getting is just DDR memory, and
therefore any memory that conforms to the DDR standard will work on your
mobo. Even slower ones, but they'll just run slower on your system, of
course.

Currently, the most popular type of memory is DDR2, so the older DDR
memories are being phased out, and likely the only stock that is left is
the fastest versions of DDR. So that's why you can't find DDR-333/PC2700
memory anymore, because now they only stock the fastest DDR-400/PC3200
memories. On the other hand, if you were interested in DDR2 memory, then
you'll have all kinds of choices such as DDR2-533/PC4200,
DDR2-667/PC5200, or DDR2-800/PC6400.

I'd also like some opinions on which brand of RAM I should get. Kingston
and Samsung are ubiquitous where I live, so the choice comes down to one
of those. Both brands are about the same price, with the Samsung being
marginally cheaper.

Brand-name doesn't matter, just make sure you buy two of exactly the
same brand at the exact same time, if you're going to be matching it up
for dual-channel operation, otherwise that'll show up as single-channel.

Dual-channel vs. single-channel is another way of increasing the speed
of Dram, with dual-channel being faster than single-channel, obviously.

Finally, would a 128 MB stick of 266 MHz DDR RAM be able to run in the
same computer as, say, a 512 MB stick of 400 MHz DDR RAM? If so, would
using both at the same time degrade the performance of the faster RAM?

Yes, the faster RAM would be slowed down to the speed of the slower RAM.
So it's best to completely remove the old RAM, if you want to gain the
performance advantage of the newer RAM.

As for mail-ordering within Canada, try this site:

www.pricegrabber.ca

Personally, I prefer to do my business with bricks'n'mortar stores
rather than online.

Yousuf Khan

 

[Andrew Smallshaw]

None of those risk factors change whether the results of
data calculations are important.

I would say ECC is appropriate for any even slightly
critical application, not just "the most mission critical".
You spend a few bucks more for better PSU, case, processor,
etc, why not the memory? Your data links usually have error
correction, as does a hard drive internally, as does the
processor cache, but main memory is a weak link in data
integrity.

Well, some of these factors _can_ affect calculations in the same
manner as bad memory - e.g. anything can happen with a brief power
outage that a regular PSU can _just_about_ bridge, including
incorrect calculations in the CPU, bad data on the bus lines or
whatever. However, I'm not questioning the fact that ECC is
extremely useful and yes, and aid to reliability. What I am
questioning is whether it should be regarded as a priority.

How often do you see bad hard drives, or blown PSUs, or have a
machine cut out in a power cut? These are a computer's weak points
so it makes sense to protect them. It's a little more difficult
to diagnose memory errors in a non-ECC PC because they would usually
appear to be much-more-likely software problems.

However, look at a machine equipped with ECC memory. How often do
you see memory errors logged? Approximately never. Cast your mind
back ten or twelve years when even commodity machines had parity
memory. How often did you see the BIOS message saying it had frozen
the system because of a parity error? I only ever saw it once.
While my memory is vague ISTR that I discounted it at the time as
it was from a system with other hardware problems. Ask yourself
why parity was removed from memory. Yes, it did save money but
why did the computer industry en masse decide that it could safely
be dispensed with?

In short ECC will improve a system's reliability, but not by much.
You are far better off spending the money elsewhere, looking at
more likely causes of failiure, and considering backup, redundancy
etc first. Only when those have been covered is it worth worrying
over whether your machine has ECC memory or not.

 

[kony]

Yes, it did save money but
why did the computer industry en masse decide that it could safely
be dispensed with?

Because they don't particularly care if a customer's
calculations/etc end up wrong if it's not guaranteed for
some critical use. The industry didn't actually abandon it
for critical uses.

 

[krw]

Well, some of these factors _can_ affect calculations in the same
manner as bad memory - e.g. anything can happen with a brief power
outage that a regular PSU can _just_about_ bridge, including
incorrect calculations in the CPU, bad data on the bus lines or
whatever. However, I'm not questioning the fact that ECC is
extremely useful and yes, and aid to reliability. What I am
questioning is whether it should be regarded as a priority.

Priority? NO, but for an 11% uplift over *CHEAP* DRAM, it's
surprising it's not standard again. I have ECC memory on my
"desktop" (at a cost *way* over 111%) and would have bought it for my
laptop, if it were available. Bit-rot is a PITA.

How often do you see bad hard drives, or blown PSUs, or have a
machine cut out in a power cut? These are a computer's weak points
so it makes sense to protect them. It's a little more difficult
to diagnose memory errors in a non-ECC PC because they would usually
appear to be much-more-likely software problems.

Right. Just because you can blame it on M$ doesn't mean it is. It
is *nice* to know when a component is failing. As you point out,
it's extremely difficult to diagnose memory problems. ECC/Parity
would make it far simpler.

However, look at a machine equipped with ECC memory. How often do
you see memory errors logged? Approximately never. Cast your mind
back ten or twelve years when even commodity machines had parity
memory. How often did you see the BIOS message saying it had frozen
the system because of a parity error? I only ever saw it once.
While my memory is vague ISTR that I discounted it at the time as
it was from a system with other hardware problems. Ask yourself
why parity was removed from memory. Yes, it did save money but
why did the computer industry en masse decide that it could safely
be dispensed with?

I see them on my "desktop" system. I've come to the conclusion that
they're ghosts cause by a BIOS problem, but they're there.

In short ECC will improve a system's reliability, but not by much.
You are far better off spending the money elsewhere, looking at
more likely causes of failiure, and considering backup, redundancy
etc first. Only when those have been covered is it worth worrying
over whether your machine has ECC memory or not.

It's a cheap thing to do to catch a difficult problem to diagnose.
If you've ever suffered a severe case of bit-rot I'm sure you would
be a little more sensitive to sources of errors.