Jump to content
Corsair Community

TWIN2X2048-6400 and TWIN2X1024-6400C4 together?


regmysoft

Recommended Posts

Hello, I have currently 2GB RAM and want to add more memory. From what I read on XP 32 bit, it's best to upgrade to 3GB , adding 2x512 RAM so it's still dual channel.

 

Can I add this memory : Corsair TWIN2X1024-6400C4 - CL4 (2x 512) ?

 

Will this CL4 work with with existing CL5? Will it degrade current speed?

 

 

Thanks

Link to comment
Share on other sites

It's never recommended mixing memory of different part numbers / sizes / settings. You'd proabably have to lower the speed and raise the timings to try to get it stable. Not worth it IMHO.

 

Stick with the 2 GB you already have.

Link to comment
Share on other sites

The premanufactured PC companies have to do some sort of mixing to sell the 3GB equipped machines for 32-bit operating systems, so its not out of the question. They'd typically use chips from the same vendor/line to help with compatibility. Don't expect to anything aggressive with timings. Like Wired says, you'd have to configure everything to the lowest common denominator (CAS5 across the system even though one pair can run CAS4) ... and account for potential timing reductions due to running 4 modules (I'm having to run my 1066 RAM at 800 since I have all 4 sockets filled). Keeping dual channel would be key. Otherwise, you might lose more performance from bandwidth than you gain from the increased memory size. In all reality, unless you're doing something link video or photo editing, 2GB is pretty ample for XP.

 

If you still *need* to run the 3-ish GB that a 32-bit OS will give to you, you might want to think about running a 2x2GB kit instead. 2x2GB kits seems to be the sweet spot for $/GB (at least for the one online vendor I looked at). You can still find a good 4GB TWIN2X kit for $20-15/GB (maybe closer to $15-10/GB if you don't mind rebates). If a 64-bit OS is in your future, you'd be able to take advantage of the full amount of memory.

 

Good luck!

Link to comment
Share on other sites

Thanks guys.

 

More memory would really help as I'm heavy Photoshop user. I know about the 2gb per processs Windows limit, still one Gb RAM would help other processes running.

 

Running at CL5 is not a problem for me.... what is question how would timings decrease overall performance.

 

Slinger: can 2x2 GB run as dual channel ? Doesn't Windows simply cut it off to 3Gb an amke sit only single channel? Then 2x2Gb doesn't make any sense...

Link to comment
Share on other sites

There is no such thing as Dual Channel memory, as this is a property of the memory controller in how it handles memory. This is why you can place memory in different slot configurations on a motherboard and it will register as single or dual channel. In otherwords, it has NOTHING to do with the OS, hence why it says single / dual channel on one of the boot screen.

 

Windows doesn't cut it off at 3 GB. It's more complicated than that.

Link to comment
Share on other sites

Thanks guys.

 

More memory would really help as I'm heavy Photoshop user. I know about the 2gb per processs Windows limit, still one Gb RAM would help other processes running.

 

Running at CL5 is not a problem for me.... what is question how would timings decrease overall performance.

 

I only see that your existing memory is CL5, but I'd guess its DDR2-800 (PC2-6400). You're currently running at CL5, so since you're adding CL4 memory (and timing it less aggressively at CL5), you should be able to still get it to run at 800 MHz. Based on Ram Guy's feedback in my situation, it sounds like the worst case is that you'd have to drop to DDR2-667 with 4 modules. I'd bet you'd get it working at CL5 @800 MHz.

 

If you can maintain your current timings, performance should stay pretty much the same. If you had to drop to DDR2-667, you'd lose some bandwidth. For example, memtest was reporting my memory bandwidth at roughly 4400 MB/s at 1066 MHz. It drops to 4050 MB/s when I drop my RAM speed to 800 MHz. Going from CL4 to CL5 was only a 50-100 MB/s difference. If your photo editing is requiring your system to constantly slosh virtual memory back and forth from the hard drive (a device that transfers on the order of 100 MB/s) ... having more memory (even with reduced latencies ... running at roughly 4000 MB/s) to avoid the paging should make the system feel faster. If you aren't paging out virtual memory that often, then your 2GB is probably fine.

 

The one thing you might have going against you is that the TWIN2X modules are probably rated to run at 2.1V (for full advertised speed...CL4). Double check what your current memory is rated for (standard is 1.8V). Since you'd be running the TWIN2X at CL5, you should be able to 'undervolt' it closer to the standard... The TWIN2X should be able to run at the standard JEDEC settings. Run memtest86+ to make sure its stable. Ram Guy also recommended that I bump my northbridge (MCH voltage for my Intel P35 board) voltage +0.05V to 0.2V to facilitate the 4 module configuration.

 

Slinger: can 2x2 GB run as dual channel ?

 

2x2GB can be used by a dual channel memory controller. The Dual Channel memory controller just needs 'compatible' modules to make a 128-bit interface from the two 64-bit wide modules.

 

Doesn't Windows simply cut it off to 3Gb an amke sit only single channel? Then 2x2Gb doesn't make any sense...

 

32-bit Windows only has 2^32 (a little over 4 billion...4GB) of memory space to map 'everything' that requires a memory address. What happens with Windows is that it ends up having to map other 'memories' on top of the 4GB of DDR2. The BIOS...graphics cards RAM...PCI memory space...legacy memory mapped IO... all subtract from the 4GB virtual memory space that Windows can work with. For example, if you have a graphics card with 128MB of RAM and drop in a 1GB RAM GPU... you'll end up with less address space left for physical system memory. It seems that most people are reporting somewhere between 3GB and 3.5GB of usuable memory... but it all matters how Windows carves up the address space for your particular hardware.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...