Athlon 64 memory parity

[Paul Missman]

Guys,

I'm currently running an Opteron system, and am thinking of experimenting
with a second, Athlon 64 based system, for cost reasons. It is much cheaper
to put together an Athlon 64 system, as the CPU is cheaper per MHz, and the
non-ECC memory is cheaper than the ECC memory needed by the Opteron chip.

However, the system will be doing critical data calculations. I can afford
to have it crash with a memory parity error and then be rebooted. I cannot
afford to have bad data from an undetected parity error get into the output
data.

So, is anyone currently running an Athlon 64 system with parity memory and
with the motherboard checking for parity errors? If so, what brand and
model of motherboard?

Thanks,

Paul Missman

 

[JK]

Guys,

I'm currently running an Opteron system, and am thinking of experimenting
with a second, Athlon 64 based system, for cost reasons. It is much cheaper
to put together an Athlon 64 system,

Not really, as for example an Opteron 150 is only $615, while the Athlon 64
FX-53 socket 939 is $839. The Athlon 64 FX-51(this is also socket 940 though!)
is $745, while the Opteron 148 is $350. If your application doesn't benefit much
from a meg L2 vs
512K L2, then you could go for Athlon 64 3500+ at around $370. If I was in your
place,
I would probably choose an Opteron 148.

as the CPU is cheaper per MHz, and the
non-ECC memory is cheaper than the ECC memory needed by the Opteron chip.

However, the system will be doing critical data calculations.

That would be even more of a reason to go for an Opteron.

 

[Tony Hill]

I'm currently running an Opteron system, and am thinking of experimenting
with a second, Athlon 64 based system, for cost reasons. It is much cheaper
to put together an Athlon 64 system, as the CPU is cheaper per MHz, and the
non-ECC memory is cheaper than the ECC memory needed by the Opteron chip.

However, the system will be doing critical data calculations. I can afford
to have it crash with a memory parity error and then be rebooted. I cannot
afford to have bad data from an undetected parity error get into the output
data.

So, is anyone currently running an Athlon 64 system with parity memory and
with the motherboard checking for parity errors? If so, what brand and
model of motherboard?

Motherboard doesn't play any part of this, it's all in the chip, and
all Athlon64 chips support ECC fully. That's part of the beauty of
bringing the memory controller on-die, AMD doesn't have to depend on
low-budget motherboard manufacturing doing sketchy implementations
here, it all just works.

Note: I'm assuming by "parity" you mean ECC, as parity memory hasn't
actually been used in about 15 years. It was replaced long ago by
ECC. Also note that the Opteron does *NOT* require ECC memory (though
it's HIGHLY recommended), but they do require *registered* memory.
Registered and ECC are two totally different things.

 

[Grumble]

I'm currently running an Opteron system, and am thinking of
experimenting with a second, Athlon 64 based system, for cost
reasons. It is much cheaper to put together an Athlon 64 system,
as the CPU is cheaper per MHz, and the non-ECC memory is cheaper
than the ECC memory needed by the Opteron chip.

I may be wrong, but I think registered/buffered and ECC are two separate
issues, e.g. Kingston sells ECC Unbuffered DDR SDRAM DIMMs.

http://www.ec.kingston.com/ecom/configurator/PartsInfo.asp?ktcpartno=KVR400X72C3A/512

You'll find a list of compatible motherboards.

For example, the ASUS K8N-E Deluxe (socket 754, thus single channel)
supports both ECC and non-ECC unbuffered DDR SDRAM.

http://www.asus.com/prog/spec.asp?m=K8N-E Deluxe

However, the system will be doing critical data calculations. I can
afford to have it crash with a memory parity error and then be
rebooted. I cannot afford to have bad data from an undetected parity
error get into the output data.

I suppose ECC would help.

 

[Mannr]

Motherboard doesn't play any part of this, it's all in the chip, and
all Athlon64 chips support ECC fully. That's part of the beauty of
bringing the memory controller on-die, AMD doesn't have to depend on
low-budget motherboard manufacturing doing sketchy implementations
here, it all just works.

Note: I'm assuming by "parity" you mean ECC, as parity memory hasn't
actually been used in about 15 years. It was replaced long ago by
ECC. Also note that the Opteron does *NOT* require ECC memory (though
it's HIGHLY recommended), but they do require *registered* memory.
Registered and ECC are two totally different things.

Dear Tony,

So, you're saying if I put (unregistered?) ECC memory in an Athlon 64
system it will work? What about 754 vs 940 sockets? Will they both work?
Could you suggest a high quality board (Tyan, Asus, etc) for Athlon 64
that has known support for ECC?

Also, what happens if I put registered (ECC) memory in a socket 754 or 940
board? Will it work or fail. In the past (Intel chips) I could usually
use registered memory in any machine, but that may have changed.

I absolutely need ECC. So I was considering getting a Tyan dual 939 chipset
board (single or dual) and using an single Opteron 14[0-8] chip in it. But it
would be a lot cheaper to use the more popular 754/940 socket designs.

Thanks,
Richard

 

[Grumble]

So, you're saying if I put (unregistered?) ECC memory in an Athlon 64
system it will work?

Several motherboards do support both ECC and non-ECC unbuffered DDR
SDRAM DIMMs (are we swimming in a sea of acronyms, or what!). I cited
the ASUS K8N-E Deluxe (socket 754) earlier. The user manual states:

You may install 64MB, 128MB, 256MB, 512MB, and 1GB unbuffered ECC
and non-ECC DDR DIMMs into the DIMM sockets using the memory
configurations in this section.

Master ECC Enable
Enables or disables support on all nodes for ECC [...]

What about 754 vs 940 sockets? Will they both work?

Socket 940 is for Opteron which requires registered memory. I don't
think anybody (??) manufactures non-ECC registered memory.

Could you suggest a high quality board (Tyan, Asus, etc) for Athlon 64
that has known support for ECC?

Socket 754 or 939?

You could start here:
http://www.ec.kingston.com/ecom/configurator/PartsInfo.asp?ktcpartno=KVR400X72C3A/512

I absolutely need ECC. So I was considering getting a Tyan dual 939 chipset
board (single or dual) and using an single Opteron 14[0-8] chip in it. But it
would be a lot cheaper to use the more popular 754/940 socket designs.

It seems you have 939 and 940 mixed up.

Socket 754 = Athlon 64, single channel memory controller
Socket 939 = Athlon 64, dual channel memory controller
Socket 940 = Opteron

 

[Grumble]

Socket 940 is for Opteron which requires registered memory. I don't
think anybody (??) manufactures non-ECC registered memory.

http://www.lostcircuits.com/memory/reg_ddr/

Briefly, ECC has nothing to do with Registered DIMMs, it is mere
coincidence that the two features are usually implemented together for
the simple reason that the boards that require Registered DIMMs are
usually working non-stop and have a need for ECC to avoid accumulation
and propagation of soft errors that occur statistically over time. For
the memory vendors, the trade-off of carrying Registered non-ECC modules
is a double inventory and, therefore, the savings incurred by leaving
off one chip per bank are not worth carrying two separate lines of
memory, especially, if the non-ECC modules are only geared towards a
splinter cell of user.

 

[Paul Missman]

Not really, as for example an Opteron 150 is only $615, while the Athlon
64
FX-53 socket 939 is $839. The Athlon 64 FX-51(this is also socket 940
though!)
is $745, while the Opteron 148 is $350. If your application doesn't
benefit much
from a meg L2 vs
512K L2, then you could go for Athlon 64 3500+ at around $370. If I was in
your
place,
I would probably choose an Opteron 148.

Since it looks like simple parity isn't an option, I'll probably stick with
the Opteron CPU line.

The price difference I was looking at was an Opteron 146 with motherboard at
$460 where ECC memory is about $150 for 512 Meg, versus an Athlon 64 3000
with motherboard for $270 where 512 Meg of non-ECC memory is $100.

At least these prices are cheaper than they were about a year ago when I
purchased my first Opteron system.

Paul Missman

 

[JK]

Since it looks like simple parity isn't an option, I'll probably stick with
the Opteron CPU line.

The price difference I was looking at was an Opteron 146 with motherboard at
$460

That sounds a bit high. You could probably get that for around $400-420

where ECC memory is about $150 for 512 Meg, versus an Athlon 64 3000
with motherboard for $270

Okay, $240-270

where 512 Meg of non-ECC memory is $100.

More like $75. The Athlon 64 3000+ will be much slower than an Opteron 146.
The dual channel memory controllers and 1 meg L2 cache vs the single
memory controller and 512K L2 of the Athlon 64 3000+ might make a big
difference in performance. Figure on average a speed grade for each,
so an Athlon 64 3400+ might on average come close to the Opteron 146.
When everything is factored in, the Opteron comes very close in price
to the Athlon 64, except for people who require large amounts of ram.
I mention the Athlon 64 FX-53 and Opteron 150 not because I thought
you should buy them, but that the chips are almost the same.

 

[Tony Hill]

Dear Tony,

So, you're saying if I put (unregistered?) ECC memory in an Athlon 64
system it will work?

Yup, unless someone motherboard manufacturer has really gone out of
their way to try and break ECC support.

What about 754 vs 940 sockets?

Socket 940 is used for the Opteron and it requires registered memory.
Socket 754 and socket 939 are both used for the Athlon64 line and they
use unregistered memory. The difference between the latter two
sockets is that 754 using single channel memory while socket 939 uses
dual channel memory, ie it requires that you add memory in matched
pairs.

Will they both work?
Could you suggest a high quality board (Tyan, Asus, etc) for Athlon 64
that has known support for ECC?

I know that Asus specifies that their Socket 754 K8N-E board supports
ECC memory, as does their Socket 939 A8V board.

Also, what happens if I put registered (ECC) memory in a socket 754 or 940
board? Will it work or fail. In the past (Intel chips) I could usually
use registered memory in any machine, but that may have changed.

If you put registered memory in socket 754 or socket 939 it will
probably fail. If you put it in socket 940 it will work just fine.

I absolutely need ECC. So I was considering getting a Tyan dual 939 chipset
board (single or dual) and using an single Opteron 14[0-8] chip in it. But it
would be a lot cheaper to use the more popular 754/940 socket designs.

Note that I think you've got you Socket 940 and 939 swapped here, but
otherwise you seem to be on the right track.

 

[Tony Hill]

Since it looks like simple parity isn't an option, I'll probably stick with
the Opteron CPU line.

Parity doesn't exist for ANY memory anymore, nor has it existed for
some time. It was replaced by ECC which can be used by either the
Athlon64 (using unregistered ECC DIMMs) or the Opteron (using
registered ECC DIMMs).

Note that Registered vs. Unregistered has pretty much nothing to do
with ECC vs. Non-ECC. These are two completely separate features.

The price difference I was looking at was an Opteron 146 with motherboard at
$460 where ECC memory is about $150 for 512 Meg, versus an Athlon 64 3000
with motherboard for $270 where 512 Meg of non-ECC memory is $100.

Looking at Crucial's prices for 512MB of PC3200 memory you've got:

Unregistered, non-ECC: $100
Unregistered, ECC: $115
Registered, ECC: $150

You could get an Athlon64 system with ECC memory for MUCH cheaper than
the price you're looking at for an Opteron.

 

[Johannes H Andersen]

Parity doesn't exist for ANY memory anymore, nor has it existed for
some time. It was replaced by ECC which can be used by either the
Athlon64 (using unregistered ECC DIMMs) or the Opteron (using
registered ECC DIMMs).

Note that Registered vs. Unregistered has pretty much nothing to do
with ECC vs. Non-ECC. These are two completely separate features.

What is 'Registered' then?

 

[Paul Missman]

What is 'Registered' then?

Registered memory has a register between the memory array and the memory bus
to avoid timing alignment errors that might cause a memory misread by the
CPU.

Using the ASUS site as a guide, things seem to break down this way:

The socket 940 pin Athlon 64 and Opteron processors want ECC, registered
memory.

The socket 939 pin Athlon 64 processors want non-ECC, unregistered memory.

The socket 754 pin Athlon 64 processors will take ECC or non-ECC,
unregistered memory.


Doing a little research:

All the Opteron processors are socket 940.

Most of the Athlon 64 processors are socket 754.

The Athlon 64 FX-51 is a socket 940.

The Athlon 64 FX-53 comes in both a socket 940 and a socket 939 version.

The Athlon 64 3500 is a socket 939.


The best guidance here is to check everything to make sure you are getting
CPU, memory, and motherboard that are compatible. Otherwise, you might wind
up with multiple mismatches.

I'm going to sitck with the Opteron for the next system, due to cache size,
memory reliability, and the promise of dual core CPUs next year.

Paul Missman

 

[Mannr]

Parity doesn't exist for ANY memory anymore, nor has it existed for
some time. It was replaced by ECC which can be used by either the
Athlon64 (using unregistered ECC DIMMs) or the Opteron (using
registered ECC DIMMs).

Note that Registered vs. Unregistered has pretty much nothing to do
with ECC vs. Non-ECC. These are two completely separate features.


Looking at Crucial's prices for 512MB of PC3200 memory you've got:

Unregistered, non-ECC: $100
Unregistered, ECC: $115
Registered, ECC: $150

You could get an Athlon64 system with ECC memory for MUCH cheaper than
the price you're looking at for an Opteron.

Thanks for the information, Tony.

So it looks like Athlon64 for workstation and Opteron for server.
All in all, a better deal than Intel!

By the way, are there any Athlon64 boards that use the AMD'8000 chipset,
or do all use VIA?

Richard

 

[keith]

Thanks for the information, Tony.

So it looks like Athlon64 for workstation and Opteron for server.
All in all, a better deal than Intel!

I looked at the difference more as MHz (A64) vs. cache and dual-channel
SDRAM (Opteron), at a particular cost point. Yes, memory cost could have
tilted it the other way, but I really didn't like the choices of A64
boards that were available at the time. Advantage Opteron.

By the way, are there any Athlon64 boards that use the AMD'8000 chipset,
or do all use VIA?

....which was the final straw.

 

[keith]

Socket 940 is used for the Opteron and it requires registered memory.
Socket 754 and socket 939 are both used for the Athlon64 line and they
use unregistered memory. The difference between the latter two
sockets is that 754 using single channel memory while socket 939 uses
dual channel memory, ie it requires that you add memory in matched
pairs.

Not required, but highly recommended. The Tyan S2875 will work with a
single stick, anyway. A waste, but it will work.

 

[Tony Hill]

Thanks for the information, Tony.

So it looks like Athlon64 for workstation and Opteron for server.

Or at the least, Athlon64 for single processor, Opteron for
dual-processor (or more). Or perhaps Athlon64 for small amounts of
memory (up to about 2GB) an Opteron for large amounts of memory.

All in all, a better deal than Intel!

Generally speaking, yes.

By the way, are there any Athlon64 boards that use the AMD'8000 chipset,

Not that I'm aware of.

or do all use VIA?

There are a number of Athlon64 boards using nVidia chipsets. If I
were to buy a new desktop system now, I would probably go for an
Athlon64 on an nVidia nForce3 250Gb based board, probably something
like the MSI K8N Neo-FSR (Socket 754.. note the 'N' for nVidia vs. the
K8V for VIA), which usually sells for a bit over $100 US. Or
alternatively if you've got a bit more cash, the MSI K8N Neo2-FSR
(Socket 939).

 

[Grumble]

Using the ASUS site as a guide, things seem to break down this way:

The socket 940 pin Athlon 64 and Opteron processors want ECC,
registered memory.

I don't think ECC is required, but you won't find any non-ECC registered
DDR SDRAM.

The socket 939 pin Athlon 64 processors want non-ECC, unregistered
memory.

I would be surprised if socket 939 Athlons did not support ECC.

Most of the Athlon 64 processors are socket 754.

Before Sempron came out, I thought AMD wanted to phase socket 754 out,
in favor of socket 939. Older Athlons have a single-channel memory
controller, i.e. 754 pins while newer Athlons have a dual-channel
memory controller, i.e. 939 pins.