Different brand of memory in the two dual slots: A problem?

Archived from groups: comp.sys.ibm.pc.hardware.systems,alt.comp.periphs.mainboard.asus,comp.sys.intel,comp.hardware (More info?)

In article <1110625013.597231.228560@f14g2000cwb.googlegroups.com>,
"aether" <vercingetorix@hotmail.com> wrote:

> There's slots 1 & 2, which are paired with the same type and brand of
> memory. (dual channel twin pack) If I were to add two additional DIMMs,
> also twin dual channel modules, but of a different brand, would this
> cause any problems? Is it preferable that all four slots be of the same
> brand and make? Or, just that 1 & 2 and 3 & 4 both be dual channel twin
> DIMMs?
>
> Example: for slots 1 & 2 I install -
>
http://www.tigerdirect.com/applications/SearchTools/ite...
>
> In slots 3 & 4 -
>
http://www.tigerdirect.com/applications/SearchTools/ite...

Well, seeing as one of your example RAMs is registered and the other
unbuffered, they aren't particularly a good pair of examples.

I'll make up an artificial example

channel 1 channel 2

slot1A [DDR333 CAS2 512MB 8 chips] [DDR333 CAS2 512MB 8 chips] slot2A
slot1B [DDR400 CAS3 512MB 16 chips] [DDR400 CAS3 512MB 16 chips] slot2B

The DIMMs sitting "across from one another", have to match in terms
of rows, columns, banks, and ranks. I could not, for example, use
an 8 chip in 1A and a 16 chip in 2A, because one is single sided
(one rank) and the other is double sided (two ranks). Internally,
the rows and columns on those chips would not match either.

The config shown in the diagram above, would run in dual channel
mode. The BIOS has to select the slower of the operating speed
characteristics, to decide what settings to use. It could, for
example, use DDR333 rate, to avoid exceeding the settings of
the first set of sticks. (It would select DDR333, if you set
the BIOS to [By SPD]. )

If you enter the BIOS and do manual settings, you could try
overclocking the memory, and run the whole thing at DDR400 CAS3,
as the DDR333 CAS2 has a fast enough CAS spec, to handle DDR400
CAS3 rate. Bumping up Trcd by one more than its spec'ed value, might
be enough to squeeze DDR400 from all the memory.

So, if you buy two pairs of RAM, sit them across from one another
so 1A=2A and 1B=2B. As long as one pair is not a gross mismatch
for the application (like using a pair of PC2100 and a pair of
PC3700), it should work OK. If you did use (2) PC2100 and (2) PC3700,
you'd have to run them at PC2100.

It is not essential for all four DIMMs to be the same brand and model
number. But there can be an advantage. If all four DIMMs have matching
rows, columns, banks, and ranks, then the BIOS can set them up to
interleave (use dynamic addressing), which will maximize the open banks
on the DIMMs. That will squeeze a few more percent memory bandwidth
from them, which will make no measurable difference to your applications.
So, this config is faster than the one above, by a few percent,
assuming the same speed and CAS settings are used in both cases.

channel 1 channel 2

slot1A [DDR333 CAS2 512MB 16 chips] [DDR333 CAS2 512MB 16 chips] slot2A
slot1B [DDR400 CAS3 512MB 16 chips] [DDR400 CAS3 512MB 16 chips] slot2B

Paul

Archived from groups: comp.sys.ibm.pc.hardware.systems,alt.comp.periphs.mainboard.asus,comp.sys.intel,comp.hardware (More info?)

> Paul wrote:
> In article <1110625013.597231.228560@f14g2000cwb.googlegroups.com>,
> "aether" <vercingetorix@hotmail.com> wrote:
>
> > There's slots 1 & 2, which are paired with the same type and brand
of
> > memory. (dual channel twin pack) If I were to add two additional
DIMMs,
> > also twin dual channel modules, but of a different brand, would
this
> > cause any problems? Is it preferable that all four slots be of the
same
> > brand and make? Or, just that 1 & 2 and 3 & 4 both be dual channel
twin
> > DIMMs?
> >
> > Example: for slots 1 & 2 I install -
> >
>
http://www.tigerdirect.com/applications/SearchTools/ite...
> >
> > In slots 3 & 4 -
> >
>
http://www.tigerdirect.com/applications/SearchTools/ite...
>
> Well, seeing as one of your example RAMs is registered and the other
> unbuffered, they aren't particularly a good pair of examples.
>
> I'll make up an artificial example
>
> channel 1 channel 2
>
> slot1A [DDR333 CAS2 512MB 8 chips] [DDR333 CAS2 512MB 8 chips]
slot2A
> slot1B [DDR400 CAS3 512MB 16 chips] [DDR400 CAS3 512MB 16 chips]
slot2B
>
> The DIMMs sitting "across from one another", have to match in terms
> of rows, columns, banks, and ranks. I could not, for example, use
> an 8 chip in 1A and a 16 chip in 2A, because one is single sided
> (one rank) and the other is double sided (two ranks). Internally,
> the rows and columns on those chips would not match either.
>
> The config shown in the diagram above, would run in dual channel
> mode. The BIOS has to select the slower of the operating speed
> characteristics, to decide what settings to use. It could, for
> example, use DDR333 rate, to avoid exceeding the settings of
> the first set of sticks. (It would select DDR333, if you set
> the BIOS to [By SPD]. )
>
> If you enter the BIOS and do manual settings, you could try
> overclocking the memory, and run the whole thing at DDR400 CAS3,
> as the DDR333 CAS2 has a fast enough CAS spec, to handle DDR400
> CAS3 rate. Bumping up Trcd by one more than its spec'ed value, might
> be enough to squeeze DDR400 from all the memory.
>
> So, if you buy two pairs of RAM, sit them across from one another
> so 1A=2A and 1B=2B. As long as one pair is not a gross mismatch
> for the application (like using a pair of PC2100 and a pair of
> PC3700), it should work OK. If you did use (2) PC2100 and (2) PC3700,
> you'd have to run them at PC2100.
>
> It is not essential for all four DIMMs to be the same brand and model
> number. But there can be an advantage. If all four DIMMs have
matching
> rows, columns, banks, and ranks, then the BIOS can set them up to
> interleave (use dynamic addressing), which will maximize the open
banks
> on the DIMMs. That will squeeze a few more percent memory bandwidth
> from them, which will make no measurable difference to your
applications.
> So, this config is faster than the one above, by a few percent,
> assuming the same speed and CAS settings are used in both cases.
>
> channel 1 channel 2
>
> slot1A [DDR333 CAS2 512MB 16 chips] [DDR333 CAS2 512MB 16 chips]
slot2A
> slot1B [DDR400 CAS3 512MB 16 chips] [DDR400 CAS3 512MB 16 chips]
slot2B
>
> Paul


I guess I'll stick with 1GB for now, and add the same brand and model #
down the road. (hope it's still out there..) From what I heard, unless
you're doing alot of video editing and whatnot, 1GB should be enough.
Thanks.

Dont be put off by computer gods - simply adjust the cas latency in the bios to run at the lower number - 1 -2 -3 etc - so they all read from the same point in the mem matrix.
If they dont run - its probable then the mem slot order - the board normally recomends the slot order. - it may look like for eg - 12 - 12 - 12 - 12 - 24 - the cas latencey may just be lowering 3 to 2 and bingo! just look for a 3 or 2 and the other 2 sticks you are adding may be 2 - just lower the 3 to 2 in that case. Makes all 4 sticks read from the same point in the memory's matrix.

Dont be put off by computer gods - simply adjust the cas latency in the bios to run at the lower number - 1 -2 -3 etc - so they all read from the same point in the mem matrix.
If they dont run - its probable then the mem slot order - the board normally recomends the slot order. - it may look like for eg - 12 - 12 - 12 - 12 - 24 - the cas latencey may just be lowering 3 to 2 and bingo! just look for a 3 or 2 and the other 2 sticks you are adding may be 2 - just lower the 3 to 2 in that case. Makes all 4 sticks read from the same point in the memory's matrix.

Overclockable sticks normally carry a cooling device - makes em look powerful but it just to keep the overclocked stick cooler - so if it aint got a cooler its prob a waste of time trying to overclock in order to match a pair of a different brand. Kingston 4 gig sticks run at the speed they are designed to run at - Corsair vengence actually run at around 1300 mhz but are overclockable to 1600 from the bios. Hope my posts helped . I 'm running odd sticks - works great!. Most of the specs can look the same, but read from a slightly diff point on the sticks matrix.... you just adjust it in the bios - normally a 2 to a one or 3 to 2 - just make sure they are set the same ( the lower number ) - Just google CAS LATENCY and read. Enjoy - Mike Chong.