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Is it ok to mix CL5 and CL6 memory in separate channels?

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December 22, 2010 12:20:18 PM

I'm upgrading a PC for a friend who I've just discovered has 2x 1GB CL5 DDR2 800 Kingston Ram.
I've already bought another 2x 1GB CL6 Kingston Value Ram modules. My question is, since these
modules will be on separate channels, will this work properly in dual-channel mode?

eg. placed in slots as follows: (CL5) (CL6) (CL5) (CL6) for dual channel.

Oh, his motherboard is an Intel DG33TL.

Thanks.
a c 347 } Memory
December 22, 2010 1:01:17 PM

ref - http://www.intel.com/support/motherboards/desktop/dg33t...

'IF' you can get them to work then you 'probably' will need to manually set the: Speed, CAS timings, and DRAM Voltage. It's generally a bad idea to mix-match RAM, and I don't recommend doing it.

Example:
800 MHz 5-5-5-15 2.0V non-ECC
800 MHz 6-6-6-14 1.8V ECC**
================
800 MHz 6-6-6-15 1.9V {Parity checking -> Disabled} + Pray it works.

The worst thing you can do is to mix ECC with non-ECC, and I'm certain your manual is clear to add only the SAME: Speed, CAS, Voltage, Type and Mfg.

CPU - | Set1 | Set2 | Set1 | Set2 |

Manual:
"Four 240-pin, DDR2 1.8 V (only) SDRAM Dual Inline Memory Module (DIMM) sockets"

"Support for:
- Unbuffered, non-registered single or double-sided DIMMs
- Non-ECC DDR2 memory
- DIMM Type and Timings listed below:
Type Timing
DDR2-800 5-5-5 or 6-6-6 only
DDR2-667 5-5-5 only "
December 22, 2010 3:09:55 PM

Totempole said:
I'm upgrading a PC for a friend who I've just discovered has 2x 1GB CL5 DDR2 800 Kingston Ram.
I've already bought another 2x 1GB CL6 Kingston Value Ram modules. My question is, since these
modules will be on separate channels, will this work properly in dual-channel mode?


Jaquith gave you the worst-case answer. The best-case answer is yes, it will work, but all the memory will run at the slowest timings (CAS 6). Your friend will have more, but insignificantly slower, memory.
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a c 347 } Memory
December 22, 2010 4:01:42 PM

For some MOBOs it's a lesser problem, but keep in mind I see this question/problem posted at least 10+ times per day. The Intel MOBO are NOT good candidates for mixing RAM. Therefore, my answer becomes more typical in this instance.

What actually happens is the BIOS sees the first set of RAM {assuming Auto} then in many instances Disables the second set to prevent errors 'thinking' the RAM on the second set is 'damaged' thereby you're left with Set2 as 'Hardware Reserved' a/k/a 'missing.' Even the chips/side cause the problem.

Therefore, the Example is the correct option; use the worst of each and manually set the BIOS. However, the best option is the have ALL the RAM the same.
December 22, 2010 6:51:37 PM

Thanks Guys, I'll try it out and see how it goes. :) 
!