Why matched pair of RAM

[raghwendra123]

It has been recommended here and everywhere else to use matched pair of ram but it still puzzles me. Why this need if specs of the ram are same and are of the same brand or for that matter of different brands. Heck, why do brands sell matched pairs like say 2X4GB. If I m correct they are of the same batch so more likely to be identical; but what is the parameter that even manufactures do not have direct control on and how it may effect other tech specs.
Where in tech specs can ram modules differ if not in voltage, speed,timings,capacity,and not sure but may be no. of chips. I would like to know the real reason behind and not experiences you may have had. Thank you.

 

[Raiddinn]

If you buy two sticks of (what it says on the pack is) 9-9-9-24 and one of them happens to be 10-10-10-27 in reality and potentially OCable to 9-9-9-24 the computer could potentially try to do a number of things that may or may not work and more or less well.

One of those things is that it could break the dual channel mode and run one stick at 9-9-9-24 and the other at 10-10-10-27 both in their own single mode channels.

It could also try to run both in a dual channel 10-10-10-27 configuration.

It might also even let you try to run both in 9-9-9-24 with one OCd and the other not.

The BIOSs of the motherboard(s) in question really determine how things like this are going to go down a lot of the time. The more you pay for the board, the more it is likely to be able to do the option you want, the less you pay for the board the more it will probably want to do what it wants regardless of what you want.

As for my wife's RAM, I don't know for sure whether or not her 800s will actually work as 800s if you OC it or if they will just never work as 800s and only ever as 667s because she would rather just run at a stable 667 than have me spend time trying to get it to work at 800 and maybe its stable and maybe it isn't.

Whereas, being the gamer that I am, I think I would acutely notice such a difference, she mostly just uses productivity apps on her computer and it matters much less whether a program opens in 5 seconds or 7.

As an aside here I do feel the need to point something out. The gains from dual channel mode afaik aren't that large and afaik they really only provide substantial benefits in the situation where somebody's RAM happens to be a major bottleneck of their computer which is a situation that I am not real sure happens often.

I think many people would be hard pressed to show - any - provable gain from running in dual channel mode rather than single channel mode.

The same for, say, opting to stick with 2x 4GB dual channel capable vs, say, 1x 4gb + 1x 8gb of a better speed and operating only in single channel mode.

But I digress.

There should definitely be a problem if two sticks in the same pack of two won't work in dual channel mode, which you kinda sorta implied in a roundabout way. Not that Corsair is a bad RAM brand or anything. I am familiar with their PSUs and they are good PSUs so I would infer their RAM would be of high quality too, but I personally use Crucial/Micron (the ones I talked about earlier) and I know about those primarily.

I also know about the Super Talent cheapy stuff my wife uses, although I wish I didn't. I would rather she lets me spend 20% more on RAM for her computer and get a brand I can trust, but she doesn't want it like that and its her PC.

Anyway, I would expect 2x RAM from the same 2x pack of premium brand to work in dual channel and I would probably try to RMA it if it didn't. If I bought 1x 4GB of premium brand A and 1x 4GB of premium brand B, however, I don't think I would stress out overly much if it wouldn't work in dual channel mode for all the reasons I spent like 8 hrs outlining. I would be happy if it did work, but I would kinda assume going in that the end result is at least reasonably unlikely to turn out optimal from my perspective.

- Edit - I just wanted to throw it out there that my brother is a civil engineer (roads) and I am pretty sure he is pretty familiar with the ins and outs of Six Sigma even if it doesn't particularly apply to his specialty that overly much. I was under the impression it was a general engineer thing on some level. I am not even an engineer and I am pretty familiar with the concepts involved from a past life as a Network Admin that had me just hanging out with engineers on and off.

 

[raghwendra123]

Looks like you swore to provide an answer here..hehehe
I would disagree here --->If you buy two sticks of (what it says on the pack is) 9-9-9-24 and one of them happens to be 10-10-10-27 in reality and potentially OCable to 9-9-9-24......
If both the SPD and sticker says its 9-9-9-24 even though it was tested for only 10-10-10-27, BIOS will run it at that setting, it it runs fine no problem, if it causes problem, which is likely, it needs to be RMAed, (the manufaccturer here took the risk of getting more items RMAed as you stated earlier. On the other hand if the sticker said 9-9-9-24 and SPD says 10-10-10-27, the company cheated and (can be sued). BIOS will run it at its SPD timings and you have to manually overclock to get 9-9-9-24 timings(if you are lucky). BIOS never tries to overclock anything on itself, it can downclock for compatibility however.

Since I am talking two good RAMs with same specs, it rules out the above situation, that might happen in real life.

----->The BIOSs of the motherboard(s) in question really determine how things like this are going to go down a lot of the time.
I tend to believe this cause some bios can run dual channel even if specs are different to bigger extent, of course at lowest common denominator. But and this is the ever persistent but, I believe if all specs including hidden specs(rank and no of chips, no of rows and columns) are same, and RAM are good in single channel they will be good in dual channel too in any board. Mileage varies if they not of same specs(including rank and all). Do you not believe this?

I know dual channel is over-hyped, but even if gain is 1fps, I am not complaining.
As for you wife's PC, you are not really overclocking the ram. just the memory controller.( 800Mhz running at 800Mhz is not overclocked) My gut says they would work fine at 800Mhz.(If you are brave enough )

And about the question on finding difference between two systems that behave identically to any possible input; you cannot. It was the basis of Einstein's theory of relativity.


About six sigma and all, All mechanical are taught that, not sure about civil, but is pretty important for them. Not so much for electrical engineers. Im not sure how do I know about six sigma, albeit a little.Try searching the terms on google, it will show autofills for mechanical,civil but not for electrical untill si of sigma.

 

[Inars]

Hi!
I mixed up 4 sticks from 2 double memory kits. How can I matching pairs, or it's not important. I'm not seek in this very deep. Windows experience Index shows 0.1 slower score, then on my machine. On PS5 same test runs slower 0,7 secs.
This machine has i2600K/P8Z68V/same 4x4 Kingston 1600 memory as my (no one can sell 2x8 gb kit).
Oh, yes, on ASUS EZ BIOS my version is Energy saver, that's PC works with Normal.
Win 7 64bit Pro

 

[vikram12apr]

is there any possibility that if i use two ram of diff. brand my system will reboot automatically without warning??

 

[jitpublisher]

is there any possibility that if i use two ram of diff. brand my system will reboot automatically without warning??

Yes, it is a possibility. This is what we refer to as a hard crash, and it can caused by memory errors or other issues like driver problems, motherboard, and another very possible culprit is your Power Supply. In fact, the power supply would by my very first suspect to check out. A "dirty" power stream can also cause this.

PS, you realize you are posting to a thread that has not been posted to for over 10 months now. You will receive quicker response's, and more of them, if you would have started a new thread. While most seasoned forum participants know that it is bad etiquette to start new threads for questions that have already been discussed before, Toms is not really moderated as a typical discussion forum. It is more a question and answer type of deal, so its best to just ask your question by starting a new thread, especially if the thread has not been active for some time.