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Mixing RAM of two different timings

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April 13, 2011 1:58:52 AM

Hey all, I recently purchased an extra 4 gigs of RAM for my rig and am concerned a bit about memory timings (yes I know it's something I should have checked before :p ).

All 8 gigs are G-Skill DDR3 1600 1.5v, so that part is fine. The difference is that one set of 2 has timings of 8-8-8-24, while the other set is at 9-9-9-24. I've installed them both in their respective dual channel slots so they don't interfere directly with each other (presumably).

I've only had my system running with the 8 gigs for about the past 20 minutes so I don't know how stable it'll be. And when I go into AsRock P67 Pro's UEFI (BIOS) utility, I find I can only change settings for DRAM as a whole. I can't seem to change the timings on the individual sticks of RAM so I have to stick with "auto" in almost every category. So if I wanted to give every stick the same timings, I don't know how I would.

The one place I was able to set a specific number on, since all sticks are identical in that respect, is the DRAM frequency at 1600 in UEFI. But in CPU-Z, one set shows 1333 while the other shows 1600, and I don't know how to fix that since I can't change RAM configs individually. If I leave it on auto I get every stick at 1333, which is unfortunate.

My question is in two parts: 1) Is there a way to specifically configure each stick through AsRock's UEFI so I can modify both the timings and the frequencies individually, and 2) is there anything particularly bad about mixing RAMs of different memory timings if they still match each other in the dual channels? Both the BIOS and CPU-Z list "overall" memory timings at 9-9-9-24, and I'm worried it may have set that for every stick.

Thanks for any help.

P.S. Also, I've never been able to get CPU-Z to recognize that my RAM is in dual channel (it's grayed out), and I'm not sure of another way to make sure.

More about : mixing ram timings

a b } Memory
April 13, 2011 2:50:49 AM

first it is not advisable to mix and match memory. It is best to use the same memory in all memory banks.

if you leave it in auto mode, the MOBO will use the SAFE settings which will allow the mobo to boot.

I would change it to 1600 and us the 9-9-9-24 settings

the 8-8-8-24 should be able to run at the slower 9-9-9-24 but not the other way around.
April 13, 2011 3:08:13 AM

"if you leave it in auto mode, the MOBO will use the SAFE settings which will allow the mobo to boot."

But that's the thing. For the DRAM frequency in BIOS I did manually change it to 1600, and I thought that would affect every stick of RAM, but apparently it doesn't. CPU-Z and AIDA64 have two of the sticks at 667mhz and the other two at 800mhz. Shouldn't they all be at 800 if I'm going with 1600 in the BIOS?

I also just noticed that one set of the sticks has a command rate of 1T and the other 2T. Not really sure what that means, unfortunately.
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a c 97 } Memory
April 13, 2011 3:28:25 AM

It is my understanding that all the ram in your pc must run at the same voltage, speed and timings. You will get only the best common denominator of specs.

In cpu-z , the memory section should show you what that common result is. It does not show the voltage, but some motherboard utilities can.
The SPD section shows what the individual sticks are capable of.

You can exercise your ram with memtest86+. It should pass a full suite of tests with NO errors.
Download the latest(beta?) version because there is an incompatibility with sandy bridge using the original version.

Some motherboards are very sensitive to mismatched ram. There can be manufacturing differences, even between the same part numbers.
That is why ram is sold in kits.

Do not worry too much about the ram. If it works, enjoy it. If it doesn't, send it back and get a proper kit.
Faster ram or better timings do not buy you much, except in synthetic benchmarks.
April 13, 2011 3:32:32 AM

Thanks for the detailed responses. Looking up command rates it seems that it can be modified as well, i.e. switching a 2T command rate to the faster 1T. Would I see any sort of performance benefit off that or should I basically just ignore these mismatched timings?

My system does seem to be running fine with the 8 gigs, after all, though I haven't done anything performance-intensive yet. Should I be looking to return these sticks and switch them for ones with the same 8-8-8-24-1T timings as my first set, or am I good to go?
April 13, 2011 3:34:04 AM

Also SPD on CPU-Z is still giving me different frequencies for the sticks. the 9-9-9-24 ones keep coming up as 1333 instead of the 1600 that they are.
a b } Memory
April 13, 2011 5:22:14 AM

8GB vs 4GB has very little overall affect on your system apart from speeding up (slightly) loading times of programs and games especially if you are multi-tasking with many programs.

You won't need to use the top speed of your RAM unless your system is heavily using graphics such as a high-end SLI or Crossfire setup. 1333MHz is more than enough for any single-GPU card on the market.

If Memtest is showing no issues and nothing is crashing on default BIOS timings my advice is to do one of the following:
1) leave the 8GB RAM on the default BIOS timings
2) remove 4GB and attempt to sell it or leave it in a static bag

I am also surprised that your motherboard would allow separate frequencies for the different RAM types. Maybe that's a new thing; it is a very new motherboard.
April 13, 2011 5:31:58 AM

I actually don't know what to think about the frequencies anymore. CPU-Z and AIDA64 still read the two sets as 1333 and 1600, respectively, but my BIOS' main screen states that they are all DDR3 1600. Not sure if the BIOS is reading the actual frequencies or simply the make and model, though. All four sticks are definitely 1600 in terms of what they should be doing in default, so maybe they are all set at 1600 and the programs are reading them incorrectly in Windows.

I do multi-task quite a bit and have noticed a nice bump in overall performance with 8GB RAM. Haven't jumped into any games yet but doesn't some extra RAM also get passed on to the GPU?
April 13, 2011 6:00:41 AM

When looking at CPU-Z, are you taking your reading from the "SPD" tab or the "Memory" tab?
Additionally, both the memory and spd categories in AIDA64 tell you nothing of your ram's actual speed. For AIDA64, you want to get your reading from the "Motherboard" category, under "Memory Bus Properties"

Also, if you'd like, you could try another utility similar to AIDA/CPU-Z, might get a different reading. One of the free ones would be the following link: http://www.piriform.com/speccy.
a c 97 } Memory
April 13, 2011 2:18:40 PM

shadoolaw said:
I actually don't know what to think about the frequencies anymore. CPU-Z and AIDA64 still read the two sets as 1333 and 1600, respectively, but my BIOS' main screen states that they are all DDR3 1600. Not sure if the BIOS is reading the actual frequencies or simply the make and model, though. All four sticks are definitely 1600 in terms of what they should be doing in default, so maybe they are all set at 1600 and the programs are reading them incorrectly in Windows.

I do multi-task quite a bit and have noticed a nice bump in overall performance with 8GB RAM. Haven't jumped into any games yet but doesn't some extra RAM also get passed on to the GPU?


Considering the relatively low cost of ram, 8gb is good.

None of the ram is used by the gpu unless you use the integrated graphics, which with a P67 based motherboard, you don't.

Since everything seems to be working, solidly, no more needs to be done.

To satisfy yourself, do take the time to run memtest86+.
http://www.memtest.org/
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