Confused about RAM selection

[hardsteppa]

I 've just been bought an asus pundit-r barebones pc case and am
purchasing various components for it now. As this is my first foray in
pc-building i'm keeping it simple and cheap so i'm buying a celeron 2.4
ghz processor, a maxtor diamondmax plus 9 120 gb drive and an asus or
aopen cd drive. The problem i'm having is working out which RAM to
buy. Now i know that the motherboard supports up to ddr3200 and this
is what i was originally looking at, 512 mb or crucial ddr3200 RAM but
having recently read that optimum RAM performance is achieved where the
ddr number is 16 times the external bus speed of the processor. For
the celeron the external bus speed is 133mhz. This number multiplied
by 16 = 2128. Does this mean then that the ddr2100 RAM would be better
matched to this system?

cheers for any help

 

[John Doe]

celeron 2.4 ghz processor...
having recently read that optimum RAM performance is achieved where
the ddr number is 16 times the external bus speed of the processor.
For the celeron the external bus speed is 133mhz. This number
multiplied by 16 = 2128. Does this mean then that the ddr2100 RAM
would be better matched to this system?

I think you get the fastest RAM you can afford, or the best value
which satisfies your CPU's minimum need, and then set the RAM's bus
speed to 133MHz.

You probably can take care of that in the BIOS.

Others might have better opinions.

 

[Mac Cool]

hardsteppa:

Does this mean then that the ddr2100 RAM would be better
matched to this system?

buy the 3200

 

[Iain Dingsdale]

I 've just been bought an asus pundit-r barebones pc case and am
purchasing various components for it now. As this is my first foray in
pc-building i'm keeping it simple and cheap so i'm buying a celeron 2.4
ghz processor, a maxtor diamondmax plus 9 120 gb drive and an asus or
aopen cd drive. The problem i'm having is working out which RAM to
buy. Now i know that the motherboard supports up to ddr3200 and this
is what i was originally looking at, 512 mb or crucial ddr3200 RAM but
having recently read that optimum RAM performance is achieved where the
ddr number is 16 times the external bus speed of the processor. For
the celeron the external bus speed is 133mhz. This number multiplied
by 16 = 2128. Does this mean then that the ddr2100 RAM would be better
matched to this system?

I built a machine around the pundit for my parents and its fantastic. Just
buy whatever is cheapest, for 3 reasons:
1) A PC3200 module doesnt have to run at 3200, it could easily run at 2700
or 2100
2) The pundit is hardly a performance machine, if you were using it for
anything where you'd notice this kind of difference, you should get another
type of system. It does however make a nice stable and quiet all rounder.
3) I dont know where you heard the 16x thing, ive never heard it myself

 

[BigJIm]

buy the 3200 then if you want to upgrade all you need is the cpu

 

[Paul]

I 've just been bought an asus pundit-r barebones pc case and am
purchasing various components for it now. As this is my first foray in
pc-building i'm keeping it simple and cheap so i'm buying a celeron 2.4
ghz processor, a maxtor diamondmax plus 9 120 gb drive and an asus or
aopen cd drive. The problem i'm having is working out which RAM to
buy. Now i know that the motherboard supports up to ddr3200 and this
is what i was originally looking at, 512 mb or crucial ddr3200 RAM but
having recently read that optimum RAM performance is achieved where the
ddr number is 16 times the external bus speed of the processor. For
the celeron the external bus speed is 133mhz. This number multiplied
by 16 = 2128. Does this mean then that the ddr2100 RAM would be better
matched to this system?

cheers for any help

According to the manual I downloaded for this product some time
ago, the BIOS doesn't have any adjustments for either FSB or
memory clock. You can use CPUZ (http://www.cpuid.com/cpuz.php)
or a similar utility, to see how the BIOS has set up your
processor and memory.

When I look at page 58 of the downloadable manual, it says the
P4R8L motherboard has DIMM slots labelled A1 and B1. That
labelling tells me the motherboard runs in dual channel mode.
(If I saw A1 and A2, that labelling implies single channel mode.)

This article mentions that RS300 supports dual channel.
http://www.tweaktown.com/document.php?dType=review&dId=584

In terms of bandwidth balance, if the processor clock is 133MHz,
then this is quad pumped to 533Megatransfers per second. The
P4 bus is 64 bits wide or 8 bytes. That means the max
transfer rate is 533*8 = 4264MB/sec.

A DDR DIMM at 133MHz would equal 133*2*(8 bytes wide) = 2128MB/sec.
If you use two matched DDR DIMMs, and the BIOS is smart enough
to select "dual channel" mode, the max bandwidth is 4256MB/sec.

There is no point these days, to buying PC2100 memory. DDR is at
the end of its life, and if you buy some, is should be some
PC3200 which you can resell. Something PC3200 or faster will
keep its resale value, while PC2100 will be harder to get rid
of.

The DDR rate of the memory is backward compatible. That means
some PC3200 can be run at DDR400, DDR333, DDR266, or DDR200.
In this case, if you bought some CAS3 PC3200, it would become
CAS2 PC2100 memory, and CAS2 is as fast as you can go.

If you look here, you can see that 512MB CAS3 PC3200 is the
most popular memory for this system. Two sticks at $86 a
piece would cost you $172.

http://www.crucial.com/store/listpa...ops&mfr=ASUS&cat=RAM&model=Pundit-R&submit=Go

If you only put one stick of RAM in the system, then
the bandwidth balance won't be quite as good. But the
computer will still run. It just won't be as peppy while
doing Photoshop (a memory intensive application).

HTH,
Paul

 

[Bill Turner]

I think you get the fastest RAM you can afford

___________________________________________________________

Good advice, because in a couple of years your present box will be
obsolete and you can move the RAM to the next one. Been there, done
that.

 

[John Smithe]

I 've just been bought an asus pundit-r barebones pc case and am
purchasing various components for it now. As this is my first foray in
pc-building i'm keeping it simple and cheap so i'm buying a celeron 2.4
ghz processor, a maxtor diamondmax plus 9 120 gb drive and an asus or
aopen cd drive. The problem i'm having is working out which RAM to
buy. Now i know that the motherboard supports up to ddr3200 and this
is what i was originally looking at, 512 mb or crucial ddr3200 RAM but
having recently read that optimum RAM performance is achieved where the
ddr number is 16 times the external bus speed of the processor.

I wouldn't call it 'optimum', but 16X the physical bus speed equals the
PCxxxx rating for DDR SDRAM memory. It is more like just matching CPU spec
to memory spec. Faster memory will work but may be a waste of money since
your CPU will not go any faster than PC2100 even with faster memory. (I'm
ignoring overclocking.)

For
the celeron the external bus speed is 133mhz. This number multiplied
by 16 = 2128. Does this mean then that the ddr2100 RAM would be better
matched to this system?

cheers for any help

PC2100 is the correct match for your CPU. That is to say, your CPU can
only go as fast as PC2100. The CPU speed and the memory speed will be the
same. Faster memory, i.e. PC3200, will work but it will be run at PC2100
speeds. PC2100 should be less expensive.

If your motherboard AND cpu BOTH support 'Dual Channel' memory mode,
install two sticks of memory, with matched spec's. Don't pay more for a
'Dual Channel Kit'. All you need is two matched sticks. Get whatever is
cheaper, a 'kit' or a pair of sticks with the same spec's. To ensure
matched spec's, get two sticks from the same manufacturer with the same
part number, that is all a 'Dual Channel Kit' really is. Memory is NOT
'Dual Channel', memory controllers and motherboards are 'Dual Channel'.
Sometimes the memory controller is in the northbridge chip. Yours probably
is, being Intel based. Sometimes the memory controller is in the CPU.
This is true of some AMD CPU's, i.e. Athlon64's.

 

[hardsteppa]

cool, cheers for all your help, the 3200 was only £3 more expensive so
i've gone for that