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Discussion Starter #1
Couldn't find a sub-forum for memory, figured this would be the best place...

Does anyone know of a web-site that breaks down all the different kinds of memory and explains what they are and how they are different from each other. I want to learn more about memory, and ask questions (here), but think I should read about all the general stuff first so as to not waste time asking basic questions.

Thanks in advance.

Barney
 

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The Gist...

Thanks, drwng! I read through the whole thing. Lots of techspeak, but one thing I think I understood is that the difference in "speed" for memory has nothing to do with the actual sticks themselves.

They are all manufactured exactly the same. What's different is how they performance test at the factory. Sticks that test well are "faster", those that test less well are "slower".

Did I understand this right ?

If so, it's an amazing revelation.

Especially the part where it appears that you can get low-cost memory to run almost as fast as high-speed memory, as they are (physically) identical, and the difference between them in performance is (sometimes) negligible.

Does this sound right ?

The article makes a pretty powerful arguement against wasting money on high-end memory, if I read it right.

Did I ?
 

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It is best to buy quality Memory. :sayyes:
Value memory is cheaper and some still has the life time warranty if you do not mind taking it back and fixing the corrupt files that it has created if they can be fixed. :4-dontkno
Most of the tests are short, :sayyes: Hours or days at the most.
 

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Oldmn...

Value memory is cheaper and some still has the life time warranty if you do not mind taking it back and fixing the corrupt files that it has created if they can be fixed.
Again, as I understood the article from drwng, "Value Memory" is defined by the article only in terms of it's clock speed. The good stuff is sold as PC3200; memory that does not perform well in tests is sold as slower memory. Otherwise they are the exact same stuff.

If I understood the article right.

During my research, I ran a filtered search for individual sticks of 1 Gbyte RAM on NewEgg. NewEgg is only selling about 10 or so different 1 Gbyte Ram right now. One thing I noticed is, regardless of price, ALL of the memory listed by NewEgg had a Lifetime warranty from the different manufacturers.

So from this I am wondering exactly what "Cheap" memory is. I wonder if NewEgg's selection is representative of the overall markey for memory, or if NewEgg is only selling memory that is "better" than what can be found elsewhere. Another thing I noticed is that there isn't a huge difference in price between the low and the high-priced memory at New Egg. A stick of 1 Gbyte goes from about $92.00 at the low end to about $130.00 at the "top of the line". And I didn't see much difference between the low and the high in terms of technical specifications. At least not enough to justify the extra $38.00.

Another thing I noticed is, (at least in the single stick, 1 Gigabyte catagory) NewEgg has got the lowest price compared to every other Seller I saw.

And again, this is just what I THINK I am seeing, I am wondering if NewEgg is selling high-quality memory at rock-bottom prices. I am looking for 2 sticks of 1 Gbyte PC3200 right now, so any help in this area will be of great value to me.
 

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greetings and yabba dabba doo

low end memory will show its worth on resourse intensive apps, [ games, video editing, ect. ]

heat is the 1st enemy of ram, so if you want to go with the cheaper modules, invest in heat spreaders.

higher priced memory usually can achieve tighter timmings [ better performance ] and are overclockers delight, such as corsair twinx , kingston hyperx, and so on.

to me getting cheap memory is like buying a middle of the road power supply, i wouldnt--imho.

regards
 

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The Value name brand memory (i.e. corsair Value Select, OCZ value series, Kingston ValueRAM, etc.) is always better than generic.
 

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If you need memory for a machine, do not worry about the crash course.

If your motherboard is supported, this download utility will tell you what you need and this vendor has good direct pricing. They are a major OEM memory supplier as well.

Download and run Check My Computer

JamesO
 

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The Value name brand memory (i.e. corsair Value Select, OCZ value series, Kingston ValueRAM, etc.) is always better than generic.
most definately

and as we all know, some boards are quite picky in regards to ram specs and manufacturers.
 

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Discussion Starter #11
How Important are Timings ?

I've been reading a lot about Memory, and have some questions about Timings.

I see numbers like "3-3-3-8" and "2-2-2-5", and while I don't necessarily need to know exactly what these numbers mean (although it might be useful), I would like to know how these numbers directly affect performance.

The purpose of the question is to determine the difference in performace by the memory on the system, while considering the difference in cost.

First, what is the range of these numbers, lowest to highest ?

One article I read said that the lower the numbers, the better (faster) the RAM. So my question is, "How low is low, and how high is high ?"

And what is the difference in actual performance between the lowest in the highest ?

Is the performance TWICE as fast from the lowest to the highest (within the same "speed class" of memory, obviously) ?

Or is the difference negligible, like say 10% (or even less) ?


Also (bonus question for extra credit), are any of these numbers more (or less) important (as it indicates performance) as the others ? The article also said that the "CAS Latency" number was irrelevant (is this true?), and I am wonder about the relative importance of the 4 Timing numbers (to each other).

Thanks in advance,


Barney
 

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This was copied from the website drwngflies had posted above. It might answer most of your questions.

Latencies - Basics

Example..

2-2-2-5

From left to right..

tCL-tRCD-tRP-tRAS

(The "t" denotes "tick")

tCL/CAS - Column Address Strobe - An electronic signal that determines which column is read or written to. You have to combine a CAS with a RAS to define a location. Lower is better.

tRCD - RAS to CAS delay - The name given to the delay that occurs when a row is activated to when the column is activated and thus data can be written to or read from. Lower is better.

tRP - RAS precharge - The delay between deactivating the current row and selecting the next row. Lower is better.

tRAS - Active to precharge delay - How long the memory has to wait before the next access cycle can begin. tRAS is not an exact science, lower is not always better. There was a thoery that the fastest/safest tRAS value to use was decided by CAS + tRCD + 2. E.g. if your timings were 2-2-2, the ideal tRAS value would be 6... but I disagree with this. I feel you need to work out for yourself which performs best for you. The difference will be extremely minimal but if you're going to manually define the tRAS at all you may as well do it properly. You can use SiSoft SANDRA memory bandwidth benchmark to compare.

Command Rate (1T/2T) - Memory access starts with the chip select. The command rate (CMD) decides how many clock cycles that chip select process needs before it can be executed. 1T is faster, 2T can often help with stability.
*CPC (Command Per Clock) : CPC Enabled = 1T, CPC Disabled = 2T.

Few quick notes...
tRCD and tRP have the biggest impact on performance. CAS does not. I believe this is mainly because altering the CAS value you are all familiar with adjusts only the read speed. To adjust the CAS write speed also you need to alter the tCWL.

CAS 1.5
CAS 1.5 does not exist. I don't know what gets set, but it's not 1.5! Look below.. see the option for CAS1.5 in the A64's memory controller? Noo.

000b = reserved
001b = CL=2
010b = CL=3
011b = reserved
100b = reserved
101b = CL=2.5
110b = reserved
111b = reserved

It is a name, that's all, a marketing gimmick. It looks cool, but there is no performance gain at all. In fact, it's often considered slower and this is why you may experience greater stability @ "1.5" than 2. It's similar to tRAS = 00, it doesn't exist because it's reserved but I know for a fact it adds stability at very high TCCX speeds.
You cannot really bench CAS"1.5" vs CAS2, though, since the margin of error is so small.

I know the above won't apply to the majority of you but maybe someone somewhere out there will be wondering.

Don't get your hopes up
When I say "biggest impact on performance" I don't mean you will see major FPS boosts in games. The difference will really be noticable in benchmarks only. A lot of people here will tell you not to even bother with adjusting latencies given how little they effect system performance but think of all the small tweaks you can do to your system to improve performance, and think what they add up too - a nice boost. And to the tweaker/bencher, latencies make a big difference.

To demonstrate my point....

How memory timings affect A64 performance: http://www.xtremesystems.org/forums...ead.php?t=48634

2-2-2-5 vs. 3-4-4-8: http://www.gamepc.com/labs/view_con...00xl&page=1

2-2-2-5 vs. 2.5-4-4-8 & 1T vs. 2T on A64: http://techreport.com/etc/2005q4/me...cy/index.x?pg=1
 

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Discussion Starter #13
The Article...

I read the article, and it raised more questions than it answered, LOL.

What I am looking for is a more "hands-on" understanding of memory at this point. I'm planning to buy, understand that there are differences in quality as well as price, and am trying to get a sense of where "adequate value" may be found.

In short, I don't want to spend money on performance I can't appreciate, nor do I want to FAIL to purchase performance that is useful as well as economical.

Is there a crash-course somewhere on how to do this ? Seems like it would be a pretty common situation.

Today's question is:

Exactly what is a "matched pair" for memory ? Is it simply two sticks of the exact same memory, or is there some other quality that can only be satisfied by SOME memory and not by others (even if they are exactly the same thing).

Thanks again & in advance.
 

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I don't do a lot of heavy gaming or overclocking in that matter so latency is usually one of the last things I look at. Basically, when I pbuy memory I look at the name brand and the price. There are some brands I stick with and some I stay away from. I have never seen the need to make sure that I have low latency memory. I never really had the time to experiment with latencies of memory. Much like overclocking. I never seen the need to run your CPU at a higher clock speed just to squeeze a few MHz out of it. You usually never notice the difference in the speed. Most the time it will leave you with a burnt up CPU and/or components or a system in an unfavorable condition in the future.

Conclusion. I don't think that an average consumer will notice the difference in latencies of memory.
Barney Rubble said:
Today's question is:

Exactly what is a "matched pair" for memory ? Is it simply two sticks of the exact same memory, or is there some other quality that can only be satisfied by SOME memory and not by others (even if they are exactly the same thing).
More or less matched pair or dual channel kits are modules that come from the same batch and are tested so the tolerances are the exact same for each other. These are normally used in dual channel motherboards. Dual channel motherboard have 2 memory busses and will read/write to 2 separate channels of memory. If the modules are not the same, you usually will get an BSOD error. Usually the motherboard will configure itself to single channel mode if it sees different sticks of memory or you can manually configure the MB for single channel mode.
Memory companies buy memory from different vendors. I have bought 30 sticks of Kingston memory that were the same part number but some of them had chips from Samsung, some had Elixir and some had the Kingston name on them. The manufacture will buy memory on price and supply.

So basically when you buy a dual channel kit, you are guarranted that both sticks are tesed and matching in every possible way, latency, speed and from the same batch.
 
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