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[Blazing Sword]

If I buy a motherboard that supports Dual channel, can I use regular DDR as well?

Also, can I combine the two, i.e. 2x512 Dual Channel DDR and one single 256 DDR?

thanks to all.

 

[Bregor]

There is no such thing as special dual channel RAM, it is just normal DDR RAM. However, to get the dual channel feature to work, you MUST have either just 2 or just 4 sticks of identical RAM, and put them in the correct slots on the motherboard. So mixing different types of RAM (even just RAM with slightly different timing) will mess it up. This is why manufacturers have been selling dual channel RAM kits: they come with two sticks of RAM that have been tested and verified to be similar enough to allow dual channel to work.

 

[impirius]

Just off the top of my head, don't kill me if i'm off...

- You can use regular DDR memory
- If you're running in dual-channel mode, you must use matching pairs (you can have 2x512 and 2x256, but not 2x512, a 512 and a 256)

 

[Ristamar]

- If you're running in dual-channel mode, you must use matching pairs (you can have 2x512 and 2x256, but not 2x512, a 512 and a 256)

I think certain boards have more robust dual channel support. If I'm not mistaken, my board can run 2x256 stick and 1x512 stick in dual channel mode.

 

[Bregor]

I think certain boards have more robust dual channel support. If I'm not mistaken, my board can run 2x256 stick and 1x512 stick in dual channel mode.

I really, really, doubt it. Dual channel MUST have matching pairs to work.

 

[SKluck]

Dual channel is not all or nothing. You can have some of your ram in dual channel, and some not.

If I'm not mistaken, my board can run 2x256 stick and 1x512 stick in dual channel mode.

Not sure exactly what you are saying here. Yes, the 256 sticks will be in dual channel, no the 512 will not.

 

[Ristamar]

Yeah, I might be imagining things.... it doesn't sound right in my head, either. Ignore what I said. If I find anything to support it, I'll post it here.

 

[Ristamar]

OK, here's what I was thinking of, two slots acting as a single channel (copied from an FAQ):

Q. What slots do i put my memory in to enable Dual Channel DDR (TwinBank)?
A. The manual says for 1 stick to reside in each channel. What that means is to benefit from DCDDR you should place modules in slots 1 & 3, or slots 2 & 3. Slot 1 is located closest to the Ziff Socket (black in color) slot 2 is next (blue) and slot 3 is next (also blue). Using all 3 slots can also enable DCDDR. People’s results have varied from system to system depending on what slots they put their modules in. Some get better performance with a certain configuration and some get better stability with another. You should try your own tests as they will more then likely differ from others.

Q. How do I set up Dual Channel DDR/TwinBank/DualDDR optimally?
A. In order for DualDDR memory to run at it's optimal speed, you need to have an equal amount of RAM in each channel. Slots 1 and 2 are channel 1, and slot 3 is channel 2. Right now I've got 256MB in slot 2, and 256MB in slot 3. This means 256MB in each channel. If I was to upgrade and wanted to keep full Dual DDR, I would need a 512MB stick, and put it in slot 3, and the 256MB sticks in slots 1 & 2. This would give me 512MB in each channel, and an equal balance. This would give me an optimal Dual DDR setup.
If I were to have, say, 512MB in one channel, and 256MB in the other, only 256MB of the channel with the 512MB stick would be running in Dual DDR, since the channels would not be balanced. The rest of the 512MB stick would run in standard single channel mode, giving below optimal performance.

 

[gohepcat]

I really, really, doubt it. Dual channel MUST have matching pairs to work.

Nope. My motherboard has 3 slots. 2 slots are channel A, 1 slot is channel B. I can put 2x256 in channel A, and 1x512 in channel B. I currently have this set up, and no they are not Matched pairs. All 3 were bought at different times.

HOWEVER. It's not the ideal set up, and I actually had to throttle down the timeing a tiny bit to have it run at 400Mhz.

 

[Bregor]

Nope. My motherboard has 3 slots. 2 slots are channel A, 1 slot is channel B. I can put 2x256 in channel A, and 1x512 in channel B. I currently have this set up, and no they are not Matched pairs. All 3 were bought at different times.

HOWEVER. It's not the ideal set up, and I actually had to throttle down the timeing a tiny bit to have it run at 400Mhz.

Yeah, but are they running in dual channel mode? I guarantee that the 512 stick isn't.

 

[Diablos]

I ran 2x256MB and 1x512MB on this mobo for quite a while. It works in dual channel just fine.

Make sure you buy the RAM in pairs though, some boards are picky if the RAM isn't identical.

 

[myzhi]

I ran 2x256MB and 1x512MB on this mobo for quite a while. It works in dual channel just fine.

Make sure you buy the RAM in pairs though, some boards are picky if the RAM isn't identical.

Dual channel offers 6.4 GB of bandwidth by combining 3.2 GB from ram A and 3.2 GB from ram B. If you have 3 ram sticks, your 3rd stick will only be offering 3.2 GB compare to 6.4 GB of the other 2. Thus, if you have uneven pairs, I believe dual channel mode will be disable bandwidth and your memory bandwidth will be limited to only 3.2 GB. To sure, download cpu-z, http://www.cpuid.com/cpuz.php#download, and tell use what it says under "Memory" tab with "Channell#."

 

[Diablos]

Dude I've used that prog before. Of course it said I was running in dual channel mode.

 

[myzhi]

Dude I've used that prog before. Of course it said I was running in dual channel mode.

Interesting. May I ask what MB you are using?

 

[Diablos]

Asus A7N8X Deluxe PCB 1.04 (piece of shit, I'm getting a Soltek soon). The only way to get DC working on PCB 1.04 is to use three modules, 2x256MB and 1x512MB works best.

I'm using one stick of 512MB PC3200 though, because my old 512MB DIMM was Samsung memory that was too good for my board. I could never overclock my FSB to 333 because of it. Wasn't compatible past 266FSB

 

[myzhi]

Asus A7N8X Deluxe PCB 1.04 (piece of shit, I'm getting a Soltek soon). The only way to get DC working on PCB 1.04 is to use three modules, 2x256MB and 1x512MB works best.

I'm using one stick of 512MB PC3200 though, because my old 512MB DIMM was Samsung memory that was too good for my board. I could never overclock my FSB to 333 because of it. Wasn't compatible past 266FSB

If you got free time, can you download and run Sandra, http://www.sisoftware.net/index.html?dir=dload&location=sware_dl_all&langx=en&a=. Please run the memory benchmarks. I would really like to know what you are getting. Thanx for indulging my curiousity.

 

[Diablos]

Well I don't use that memory anymore (I got rid of it) so I can't test anyway... I can test with this module though. But it's only one so it's not dual channel. I already have sandra installed, i'll test.

 

[Diablos]

Memory Bandwidth:

SiSoftware Sandra

Benchmark Results
RAM Bandwidth Int Buff'd aEMMX/aSSE : 2415MB/s
RAM Bandwidth Float Buff'd aEMMX/aSSE : 2233MB/s

Int Buff'd aEMMX/aSSE (Integer STREAM) Results Breakdown
Assignment : 2446MB/s
Scaling : 2446MB/s
Addition : 2377MB/s
Triad : 2394MB/s
Data Item Size : 8-bytes
Buffering Used : Yes
Offset Displacement Used : Yes
Bandwidth Efficiency : 90% (estimated)

Float Buff'd aEMMX/aSSE (Float STREAM) Results Breakdown
Assignment : 2442MB/s
Scaling : 2250MB/s
Addition : 2133MB/s
Triad : 2110MB/s
Data Item Size : 8-bytes
Buffering Used : Yes
Offset Displacement Used : Yes
Bandwidth Efficiency : 84% (estimated)

Performance Test Status
Run ID : A7N8X-DLX on Saturday, August 07, 2004 at 10:16:09 AM
Memory Used by Test : 256MB
NUMA Support : No
SMP Test : No
Total Test Threads : 1
SMT Test : No
Dynamic MP/MT Load Balance : No
Processor Affinity : P0
Page Size : 4kB
Use Large Memory Pages : No

Chipset 1
Model : ASUSTeK Computer Inc nForce2 AGP Controller
Front Side Bus Speed : 2x 167MHz (334MHz data rate)
Width : 64-bit
Maximum Bus Bandwidth : 2672MB/s (estimated)

Logical/Chipset 1 Memory Banks
Bank 2 : 512MB DDR-SDRAM 2.5-3-3-8CL 2CMD
Channels : 2
Speed : 2x 200MHz (400MHz data rate)
Width : 64-bit
Maximum Memory Bus Bandwidth : 6400MB/s (estimated)

Features
(W)MMX Technology : Yes
SSE Technology : Yes
SSE2 Technology : No
SSE3 Technology : No
EMMX - Extended MMX Technology : Yes
HTT - Hyper-Threading Technology : No

Cache & Memory Bandwidth:

SiSoftware Sandra

Benchmark Results
Combined Index : 3511MB/s
Speed Factor : 16.0
2kB Blocks : 15641MB/s
4kB Blocks : 16538MB/s
8kB Blocks : 16968MB/s
16kB Blocks : 13568MB/s
32kB Blocks : 11298MB/s
64kB Blocks : 10603MB/s
128kB Blocks : 6985MB/s
256kB Blocks : 5736MB/s
512kB Blocks : 1168MB/s
1MB Blocks : 1073MB/s
4MB Blocks : 1078MB/s
16MB Blocks : 1067MB/s
64MB Blocks : 1075MB/s
256MB Blocks : 1063MB/s

Float SSE Cache/Memory Results Breakdown
Data Item Size : 16-bytes
Buffering Used : No
Offset Displacement Used : Yes

Performance Test Status
Run ID : A7N8X-DLX on Saturday, August 07, 2004 at 10:18:14 AM
NUMA Support : No
SMP Test : No
Total Test Threads : 1
SMT Test : No
Dynamic MP/MT Load Balance : No
Processor Affinity : P0
Page Size : 4kB
Use Large Memory Pages : No

Processor
Model : AMD Athlon(tm)
Speed : 1.84GHz
Model Number : 2229 (estimated)
Performance Rating : PR2664 (estimated)
Type : Standard
Internal Data Cache : 64kB Synchronous Write-Back (2-way, 64 byte line size)
L2 On-board Cache : 256kB ECC Synchronous Write-Back (16-way, 64 byte line size)

Features
SSE Technology : Yes
SSE2 Technology : No
SSE3 Technology : No
EMMX - Extended MMX Technology : Yes
HTT - Hyper-Threading Technology : No

Chipset 1
Model : ASUSTeK Computer Inc nForce2 AGP Controller
Front Side Bus Speed : 2x 167MHz (334MHz data rate)
Width : 64-bit
Maximum Bus Bandwidth : 2672MB/s (estimated)

Logical/Chipset 1 Memory Banks
Bank 2 : 512MB DDR-SDRAM 2.5-3-3-8CL 2CMD
Channels : 2
Speed : 2x 200MHz (400MHz data rate)
Width : 64-bit
Maximum Memory Bus Bandwidth : 6400MB/s (estimated)

 

[Ristamar]

Asus A7N8X Deluxe

I'm using the same board.

 

[Ecrofirt]

can someone explain exactly what dual channel memory is?

 

[teh_pwn]

It's sort of like HDDs in RAID 0.

It theoretically doubles the bandwidth of your RAM, but doesn't actually increase it that much (tho, more than raid 0 does). How much of a performance boost depends on your processor.

Say you have two sticks of 512 MB of RAM that runs at 400 MHz. In dual channel it's 800 MHz. You still have a GB of RAM. Some people tend to think at first that consequently you only get 1/2 the memory but with increased speed.

These processors will take good advantage of it:

P4 800 FSB w/ HT
AMD FX socket 754 series
AMD 64 Socket 939 (including FXs)

Processors that will take a slight increase in performance:

AMD XP
P4 400 FSB
AMD 64 Socket 754 (not including FX)

Not sure about P4 533 FSB.

 

[gohepcat]

Yeah, but are they running in dual channel mode? I guarantee that the 512 stick isn't.

Yea it is. I can tell by the big "Duel Channel Mode" that comes up in the Bios screen everytime I boot the machine.

 

[Diablos]

I'm using the same board.

You may want to get rid of it, I know I am. Asus sucks.

 

[MoxManiac]

I'm fairly sure that if you run 2 sticks in dual channel and a 3rd stick alone, everything will slow down to the 3rd stick's speed.

 

[teh_pwn]

"You may want to get rid of it, I know I am. Asus sucks."

Didn't you just get rid of an MSI board? Damn man, do some research this time!

Check out some reviews from anandtech and tomshardware.

 

[tenchir]

I'm fairly sure that if you run 2 sticks in dual channel and a 3rd stick alone, everything will slow down to the 3rd stick's speed.

That's what I am thinking too. I don't know how it is possible that the third stick can do 6.4 GB of bandwidth, unless it's running at twice the speed as the other two stick.

Here's mine benchmark and keep in mind I am using dual channel and that my FSB is 133 Mhz.

SiSoftware Sandra

Benchmark Results
RAM Bandwidth Int Buff'd aEMMX/aSSE : 1689MB/s
RAM Bandwidth Float Buff'd aEMMX/aSSE : 1645MB/s

Int Buff'd aEMMX/aSSE (Integer STREAM) Results Breakdown
Assignment : 1727MB/s
Scaling : 1719MB/s
Addition : 1654MB/s
Triad : 1656MB/s
Data Item Size : 8-bytes
Buffering Used : Yes
Offset Displacement Used : Yes
Bandwidth Efficiency : 79% (estimated)

Float Buff'd aEMMX/aSSE (Float STREAM) Results Breakdown
Assignment : 1724MB/s
Scaling : 1706MB/s
Addition : 1573MB/s
Triad : 1580MB/s
Data Item Size : 8-bytes
Buffering Used : Yes
Offset Displacement Used : Yes
Bandwidth Efficiency : 77% (estimated)

Performance Test Status
Run ID : XXX on Sunday, August 08, 2004 at 7:41:04 PM
Memory Used by Test : 256MB
NUMA Support : No
SMP Test : No
Total Test Threads : 1
SMT Test : No
Dynamic MP/MT Load Balance : No
Processor Affinity : P0
Page Size : 4kB
Use Large Memory Pages : No

Chipset 1
Model : Nvidia Corp nForce AGP Controller
Front Side Bus Speed : 2x 134MHz (268MHz data rate)
Width : 64-bit
Maximum Bus Bandwidth : 2144MB/s (estimated)

Logical/Chipset 1 Memory Banks
Bank 0 : 256MB DDR-SDRAM 2.5-3-3-6CL
Bank 2 : 256MB DDR-SDRAM 2.5-3-3-6CL
Channels : 2
Bank Interleave : 2-way
Speed : 2x 134MHz (268MHz data rate)
Width : 64-bit
Maximum Memory Bus Bandwidth : 4288MB/s (estimated)

Features
(W)MMX Technology : Yes
SSE Technology : Yes
SSE2 Technology : No
SSE3 Technology : No
EMMX - Extended MMX Technology : Yes
HTT - Hyper-Threading Technology : No

I just realized something on your:

Logical/Chipset 1 Memory Banks
Bank 2 : 512MB DDR-SDRAM 2.5-3-3-8CL 2CMD
Channels : 2
Speed : 2x 200MHz (400MHz data rate)
Width : 64-bit
Maximum Memory Bus Bandwidth : 6400MB/s (estimated)

Why is there only 1 memory stick being reported??? It's the same for both of your benchmark.....

 

[DonasaurusRex]

amd socket 754 doesnt take advantage of dual channel they are single channel socket 939 does however.

 

[gohepcat]

I'm fairly sure that if you run 2 sticks in dual channel and a 3rd stick alone, everything will slow down to the 3rd stick's speed.

You are not running 2 sticks in duel channel. You are running 2 sticks in one channel (Slot 1 and 2) and one stick in the other (Slot 3).

One channel is 256x2 and one is 1x512. Both channels are 512.

If I pulled out my 512 stick the board would then be running in single channel mode. Both sticks would only be in one channel.

 

[Ristamar]

You may want to get rid of it, I know I am. Asus sucks.

Asus sucks? Asus fuckin' rocks. Every Asus board I've has performed flawlessly. You must've got a bad one.

I do have a later PCB revision. I'm pretty certain mine is 2.0.

 

[tenchir]

You are not running 2 sticks in duel channel. You are running 2 sticks in one channel (Slot 1 and 2) and one stick in the other (Slot 3).

One channel is 256x2 and one is 1x512. Both channels are 512.

If I pulled out my 512 stick the board would then be running in single channel mode. Both sticks would only be in one channel.

That makes a lot of sense, but I can see stability problems with that setup or even getting decent performance compared to the normal way of getting dual channel.

So it's basically:

3.2(2x256) + 3.2(512) = 6.4 <---Loses efficiency and stability

vs the normal

3.2(512) + 3.2(512) = 6.4


Still, why is SisSoftware Sandra only reporting 1 memory stick for his?

 

[Ecrofirt]

sorry to bump the old thread, but I've got a few questions:

How exactly does dual channel memory work? Is it like some RAID setups where you'll have two 160GB HDs, but there's parallel data on them so it acts as if there's only 1 160GB HD?

My new Dell PC has "2GB Dual Channel DDR2 SDRAM at 533MHz (2x1GB)" - if I use it as dual channel, will my PC think I only have 1GB of memory, but that memory will be faster than normal?

Also, I was thinking about picking up another GB of memory sometime near christmas. If I get 2x512 sticks, can I also use these as dual channel while i'm using the 2 1GB sticks?

just checking to find out. I'm not informed about this dual channel stuff at all.

 

[EekTheKat]

Still, why is SisSoftware Sandra only reporting 1 memory stick for his?

He mentioned in his post he's not using the dual channel setup anymore. That's probably the reason why it's reporting 1 stick.

As for Dual Channel DDR, nforce2 boards with 3 slots do in fact seem to run in Dual Channel mode with 3 sticks of ram.

Nforce2 boards seem to have a maximum support of 6 banks of memory to run in DC mode.

The reason why 2x256megs in one channel and 1x512 megs in another channel would be slower is usually due to the latency of higher density chips generally being higher than the lower density chips.

Since memory controllers generally can't run with split timings (least not to my knowledge) for each individual channel, they all generally have to run at the most common stable speeds.

Of course if your 1x512meg stick can run at 2-2-2-11 (the somewhat tested optimal timings for nforce boards), then odds are you'll be able to run all 3 sticks at optimal settings.

[edit] well manufacturers generally list something like this for nforce boards :

Supports 3DIMM's DDR 200/266/333 (Max 3Gb)
Supports 2DIMM's DDR 400 (Max 2Gb)

Implying that a 3rd dimm running in dual channel DDR would infact risk instability. If you ask around though I wouldn't be surprised if someone did get an uneven configuration working at DDR400.


The intel boards seem to be the ones hard wired with the matching pairs rule. Though I can't speak from experience since I haven't touched an intel desktop pc in ages.

My new Dell PC has "2GB Dual Channel DDR2 SDRAM at 533MHz (2x1GB)" - if I use it as dual channel, will my PC think I only have 1GB of memory, but that memory will be faster than normal?

No it should still recognize it as 2gb of ram.

 

[SlickWilly223]

Question:

How do I know if my RAM is running in Dual Channel? I'm supposed to have it in Dual Channel mode, I just want to make sure...

 

[teh_pwn]

"How do I know if my RAM is running in Dual Channel? I'm supposed to have it in Dual Channel mode, I just want to make sure.."

Check your motherboard's manual. If you PC is prebuilt, open your case up, write down your mobo's #, and look it up online. Generally there should be two colored slots that should have two identical sticks in them. Some mobos can do 4 sticks in dual channel, while others just 2.

Most mobos will enable automatically, others you'll have to go into your mobo BIOS and set it up.


"Also, I was thinking about picking up another GB of memory sometime near christmas. If I get 2x512 sticks, can I also use these as dual channel while i'm using the 2 1GB sticks?"

I wouldn't recommend that. I doubt you ever use anything close to 2 GB, and your risking taking away Dual channel. I don't think you could add on anything more for dual channel, especially different sized sticks.