Mixing CL5 and CL6 modules

[Shadowfax]

I am upgrading RAM in my old PC having motherboard Asus p5Q Pro.

Right now I have G.skill 4GBPQ 2 x 2GB 800 mhz CL5 modules working in dual channel.

Want to add additional 4GB by combining 2 x 2GB Kingston ValueRam KVR800D2N6 800 mhz which are CL6 modules.

So. will this work?

 

[bssunilreddy]

I am upgrading RAM in my old PC having motherboard Asus p5Q Pro.

Right now I have G.skill 4GBPQ 2 x 2GB 800 mhz CL5 modules working in dual channel.

Want to add additional 4GB by combining 2 x 2GB Kingston ValueRam KVR800D2N6 800 mhz which are CL6 modules.

So. will this work?

No, it will not work in Dual Channel Mode. Whichever RAM timings and Speed is lower will be taken into consideration by the system.

 

[Shadowfax]

No, it will not work in Dual Channel Mode. Whichever RAM timings and Speed is lower will be taken into consideration by the system.

See,

Ram 1 combination - G.skill 2 x 2GB 800 mhz in dual channel = 4GB but this is CL5

Ram 2 combination - 2 x 2GB Kingston ValueRam KVR800D2N6 800 mhz = 4GB this is CL6


My question is, so what will happen with this config?

Regards

 

[bssunilreddy]

See,

Ram 1 combination - G.skill 2 x 2GB 800 mhz in dual channel = 4GB but this is CL5

Ram 2 combination - 2 x 2GB Kingston ValueRam KVR800D2N6 800 mhz = 4GB this is CL6


My question is, so what will happen with this config?

Regards

Cl5 + Cl6 RAM -- Mixing
CL5 vs CL6 - [Solved] - Memory - Tom's Hardware

 

[Shadowfax]

Cl5 + Cl6 RAM -- Mixing
CL5 vs CL6 - [Solved] - Memory - Tom's Hardware

Okay great. So I will be able to put 2 new modules of CL6 ram but my existing memory will be down to CL6 from CL5.

So my total ram will be 8 GB

Sent from my A0001 using Tapatalk

 

[bssunilreddy]

Okay great. So I will be able to put 2 new modules of CL6 ram but my existing memory will be down to CL6 from CL5.

So my total ram will be 8 GB

Sent from my A0001 using Tapatalk

Yes, you will be able to run both the rams at CL6 latency only which is slower compared to CL5.

 

[Shadowfax]

Yes, you will be able to run both the rams at CL6 latency only which is slower compared to CL5.

I hope this won't make significant difference in speed. In fact I'm going to increase memory from 4 gb to 8gb. PC should run faster..right?

 

[Shadowfax]

I purchased 2 modules of Kingston ValueRAM KVR800D2N6/2G 2GB 800MHz DDR2 Non-ECC CL6 DIMM Desktop Memory

But when I checked BIOS, they are running at 667 Mhz instead of 800 Mhz. My older memory is CL5 and new memory is CL6. I read that when you mix CL5 and CL6, the resulted config runs at CL6.

Then why my config is running at 667 Mhz and where to check CL5 or CL6 setting?

Attached is the cpuz screen capture.

Thanks.

 

[SaiyanGoku]

They will run at 667 MHz only.

 

[whitestar_999]

When mixing different ram,system will run at slower of the various different ram.Your new ram maybe 800 but your older ram is most likely 667 hence the system will operate ram at 667 only.

P.S.It also depends on your mobo.It seems like you are only using newer 800MHz ram so your mobo seems to support only upto 667MHz ram.

 

[Shadowfax]

When mixing different ram,system will run at slower of the various different ram.Your new ram maybe 800 but your older ram is most likely 667 hence the system will operate ram at 667 only.

When mixing different ram,system will run at slower of the various different ram.Your new ram maybe 800 but your older ram is most likely 667 hence the system will operate ram at 667 only.

No No. Here's the situation.

Old ram - 800 hhz CL5

New ram - 800 mhz CL6

Now current system is running at 667 mhz and I don't know its CL5 or CL6. How do I check that?

My mobo is Asus P5q Pro which supports upto 1200 mhz.

But why 667 mhz?

And I suspect new ram I ordered carries sticker KVR800D2N6 but is actually 667 ? ?

 

[whitestar_999]

I edited my earlier post.Also check SPD tab in cpu-z.When a DDR2 ram runs at 667MHz it will run at CL5 only even if it is CL6 DDR2 ram.

 

[Shadowfax]

I edited my earlier post.Also check SPD tab in cpu-z.When a DDR2 ram runs at 667MHz it will run at CL5 only even if it is CL6 DDR2 ram.

New I am running latest version of cpuz but its showing blank in SPD tab. For all the 4 slots. Why so?

 

[whitestar_999]

Try running cpu-z as "admin"(right click cpu-z exe & select "run as admin").

 

[Shadowfax]

Hi guys,

I manually changed DRAM frequency in BIOS from Auto to 800 Mhz. And guess what, the information in SPD tab has appeared since then. Attached are the screen shots. I did not change CL value, rather I don't exactly understand what is cas latency and don't know how to change it. Also, I googled on dual channel memory but haven't found specific info. So I'd like to ask here.

Therefore my question is

1) My system is running as 2 sets of dual channel ram?
2) What exactly happens in my system (in theory)? Frequency gets doubled like 800 + 800 = 1600 mhz? I have 4 modules, so it is 800 * 4 = 3200 mhz?
3) Both the pairs are running at CL5?
4) What is JEDEC column which are different for G.skill and Kingston modules?

Thanks & Regards

 

[bssunilreddy]

Multi-channel memory architecture - Wikipedia

 

[whitestar_999]

Read the mobo manual(section 2.4.2) for getting answers about your queries regarding dual channel ram setup & CL5.For frequency,just read wiki entry for DDR2 ram else in simple terns answer is no for your query#2.JEDEC is an organization that set standards for RAM & every ram comes with pre-loaded JEDEC profiles which are supposed to get loaded as default depending on mobo & processor(multiple profiles are there for multiple processor/mobo combinations & the reason why a RAM will not always run at rated speed as it depends on mobo/bios/processor/ram setup).