Originally Posted by tcarlsen Interesting (and highly-advanced) stuff!
Ryan, let me ask you a pragmatic question for us regular consumers to see if this can apply to everyday decisions. How much of a performance difference, if any, would you realize by using 2 GB of Dual Channel DDR2 SDRAM memory at 800 MHz memory (two sticks) instead of the standard 2 GB of Dual Channel DDR2 SDRAM at 677MHz memory (two sticks), if you were using an Intel E4500 Core 2 processor running Vista and a 256MB video card with a 800MHz controller speed?
Or to put this another way, would you choose the 800MHz memory over the 677mHz memory if you only had to pay $10 more per stick?
Thank you.
Pay $10 more for faster memory... sure why not.
this is a fantastic question.
My Honest Answer: I don't know and here's why...
It is all about software optimization. Some software like games is highly dependent on how the actual codes are optimized: GPU dependent, GPU+GDDR dependent, GPU+CPU+GDDR dependent, GPU+CPU+GDDR+DDR and etc.
For more professional software like Video encoding, 3D rendering and compiling complex animation, it is highly dependent on the amount of RAM and how fast the CPU can store and remove data from the RAM for processing. Having superior size-frequency-latency DIMMs is an advantage. In our experience, some video and 3D rendering programs can shave 5-15% time off a job with superior memory. Even with the same RAM, the memory subsystems on the motherboard can influence the actual difference.
It depends on what you plan to use your Rig for.
Here are a few rules that my team follow:
[1] Always upgrade when the memory standard has reached the highest JEDEC speed. Thats DDR1 = 400MHz, DDR2 = 800MHz and DDR3=1600Mhz. Motherboards not reaching that milestone should not be purchased regardless of the availability of the memory modules. Simple reason: HELLUVA Memory compatibility problems with early released modules.
[2] More RAM is more important than having a fast RAM, when you have to choose between them. Avoid having OS relying on Virtual Memory when possible.
[3] Try to MAX out the RAM when possible with a single purchase, so all ICs and PCB used for your RAM is the same. Avoid incompatibility.
[4] CPU-Motherboard pairing is much more important than solely RAM performance.
[5] Memory Compatibility is more important than Performance
And my own preference... Buy what you need to kick-ass now, not what you think you might need in 6-12 months time and be happy with it. buy and upgrade the PC can be emotional, so watch out. For example... some premium DDR2 module prices were 300%-500% higher in the beginning of 2007.
A hint of what's coming in later part of the article series...
DDR compatibility problems are a rising trend. Some motherboards cannot compensate for signal uncertainties. During our validation process for a few clients, we have a fair few retail Corsair XMS DDR2-800 standard CL5 modules failing to work with at least 7 different DDR2-800 boards. The Corsair 800MHz were down graded to 667MHz, configured under Single-Channel and DRAM Voltage bump to 2.0v. Many users at home do not know their memory system is unstable.
Originally Posted by Shielder Ryan, I'm really looking forward to the full work. I've only got a physics degree, but I do try and stay abreast of things. Thanks for a great article!
Andy
thanks. some of the best conversations i had were with physicists.
IMHO, having a diploma, degree or a post-grad sure can't beat a spirited person. Take a look at giants like Bill Gates, Mike Dell, Larry Ellison, Steve Jobs, Rich. Branson + etc.
Thank you for the terrific response. So I will buy a computer with as much RAM as I can afford so that the RAM is the same. More RAM is important, and adding a different brand of RAM later could cause compatibility glitches and slightly decreased performance. And for $10 more, faster RAM might make a slight difference -- I assume especially with video and webpage loading, as opposed to CPU calculation.
Now just for the sake of curiosity and fascination with the subject of memory, let me ask you a tough question. Obviously, a computer running Vista with a Core 2 Duo Processor with 2 Gigs of cashe and 2 Gigs of RAM (2 sticks of 1 Gig RAM) is going to run faster than a Core 2 Duo processor with 1 Gig of cashe and 1 Gig of RAM. 2 + 2 > 1 + 1.
BUT, which of these two combinations would be faster?
A) A computer running Vista with a Core 2 Duo processor with 2 Gigs of cashe and 4 Gigs of RAM (4 sticks of 2 Gig RAM).
B) A computer running Vista with a Core 2 Duo processor with 4 Gigs of cashe and 2 Gigs of RAM (2 sticks of 1 Gig RAM).
Correction, I mean MB for the cashe and not GB, obviously. 1 GB RAM memory is obviously much larger than 1 MB cashe memory, but according to your article, cashe memory is of a higher level.
BUT, which of these two combinations would be faster?
A) A computer running Vista with a Core 2 Duo processor with 2 Gigs of cashe and 4 Gigs of RAM (4 sticks of 2 Gig RAM).
B) A computer running Vista with a Core 2 Duo processor with 4 Gigs of cashe and 2 Gigs of RAM (2 sticks of 1 Gig RAM).
2 + 4 = 4 + 2 ??
completemadness is right.
Here's my take and what i know...
It is not a simple 2 + 4 = 4 + 2.
Cache and RAM are two very different things. They can't be compared next to each other for a few reasons.
Cache itself is not solely used for storing data, but also computing instructions and etc. There're Data Cache and Instruction Cache. Adding one or the other in the CPU does not yield the same performance gain. The balance is unique to each CPU maker.
AMD and INTEL have different approach in the logics and algorithms used to determine what should be stored in the cache. So, having more Cache in AMD will yield different results from INTEL because of distintive optimization strategy.
IMHO AMD has slightly more efficient memory system, with hidden potential that has not been widely tapped or known.
INTEL uses larger cache for a few reasons but not limited to these...
[1] INTEL processor has more real estate for cache due to more refined lithographical fab tech (eg. 65nm or coming 45nm)
[2] INTEL has potential bottleneck issues with the FSB. more cache means, the cpu doesn't have to use the FSB pipe as much. AMD doesn't have the FSB issue. INTEL took a practical approach, but may be likely to remove the FSB design in near future.
There is a so called 'diminishing margin (or return)' with cache. There will be a time adding more cache will yield little to no tangible performance gain. You can't exactly choose the amount of cache to have. It's pre-determined, hence shouldn't be a major purchasing factor. Generally, more cache is better and the makers will make you payyyyyyyy...
In short, the number of CPU Cores, Frequency and amount of RAM are much more important factors to consider than Cache.
In a funny way, installing more RAM slows the 'aging process' for your computer, say.. in the time frame of 5 years.
If you're planning to use Microsoft VISTA, installing 4GB of RAM is preferred over 2GB. Many latest games demand larger memory footprint.
Under a 2GB system, assuming the VISTA OS will hug 1GB of RAM for itself, that leaves only 1GB for Crysis or Call of Duty 4.
More RAM cuts down on the game load time, and that's how i like my games to be.
Thanks for the article, excellent read. finally a source for correct technical facts surrounding soo many myths due to forumers. It seems a very fluent read for techs and non-techs. I will be very interested to read the next installment of your RAM paper.
Comments 26 to 32 of 32
ReplyPay $10 more for faster memory... sure why not.
this is a fantastic question.
My Honest Answer: I don't know and here's why...
It is all about software optimization. Some software like games is highly dependent on how the actual codes are optimized: GPU dependent, GPU+GDDR dependent, GPU+CPU+GDDR dependent, GPU+CPU+GDDR+DDR and etc.
For more professional software like Video encoding, 3D rendering and compiling complex animation, it is highly dependent on the amount of RAM and how fast the CPU can store and remove data from the RAM for processing. Having superior size-frequency-latency DIMMs is an advantage. In our experience, some video and 3D rendering programs can shave 5-15% time off a job with superior memory. Even with the same RAM, the memory subsystems on the motherboard can influence the actual difference.
It depends on what you plan to use your Rig for.
Here are a few rules that my team follow:
[1] Always upgrade when the memory standard has reached the highest JEDEC speed. Thats DDR1 = 400MHz, DDR2 = 800MHz and DDR3=1600Mhz. Motherboards not reaching that milestone should not be purchased regardless of the availability of the memory modules. Simple reason: HELLUVA Memory compatibility problems with early released modules.
[2] More RAM is more important than having a fast RAM, when you have to choose between them. Avoid having OS relying on Virtual Memory when possible.
[3] Try to MAX out the RAM when possible with a single purchase, so all ICs and PCB used for your RAM is the same. Avoid incompatibility.
[4] CPU-Motherboard pairing is much more important than solely RAM performance.
[5] Memory Compatibility is more important than Performance
And my own preference... Buy what you need to kick-ass now, not what you think you might need in 6-12 months time and be happy with it. buy and upgrade the PC can be emotional, so watch out. For example... some premium DDR2 module prices were 300%-500% higher in the beginning of 2007.
A hint of what's coming in later part of the article series...
DDR compatibility problems are a rising trend. Some motherboards cannot compensate for signal uncertainties. During our validation process for a few clients, we have a fair few retail Corsair XMS DDR2-800 standard CL5 modules failing to work with at least 7 different DDR2-800 boards. The Corsair 800MHz were down graded to 667MHz, configured under Single-Channel and DRAM Voltage bump to 2.0v. Many users at home do not know their memory system is unstable.
Cheers. :D
thanks. some of the best conversations i had were with physicists.
IMHO, having a diploma, degree or a post-grad sure can't beat a spirited person. Take a look at giants like Bill Gates, Mike Dell, Larry Ellison, Steve Jobs, Rich. Branson + etc.
Now just for the sake of curiosity and fascination with the subject of memory, let me ask you a tough question. Obviously, a computer running Vista with a Core 2 Duo Processor with 2 Gigs of cashe and 2 Gigs of RAM (2 sticks of 1 Gig RAM) is going to run faster than a Core 2 Duo processor with 1 Gig of cashe and 1 Gig of RAM. 2 + 2 > 1 + 1.
BUT, which of these two combinations would be faster?
A) A computer running Vista with a Core 2 Duo processor with 2 Gigs of cashe and 4 Gigs of RAM (4 sticks of 2 Gig RAM).
B) A computer running Vista with a Core 2 Duo processor with 4 Gigs of cashe and 2 Gigs of RAM (2 sticks of 1 Gig RAM).
2 + 4 = 4 + 2 ??
Aslong as your program isnt having to use the pagefile, the bigger cache will be faster
Otherwise, the ram will be faster
completemadness is right.
Here's my take and what i know...
It is not a simple 2 + 4 = 4 + 2.
Cache and RAM are two very different things. They can't be compared next to each other for a few reasons.
Cache itself is not solely used for storing data, but also computing instructions and etc. There're Data Cache and Instruction Cache. Adding one or the other in the CPU does not yield the same performance gain. The balance is unique to each CPU maker.
AMD and INTEL have different approach in the logics and algorithms used to determine what should be stored in the cache. So, having more Cache in AMD will yield different results from INTEL because of distintive optimization strategy.
IMHO AMD has slightly more efficient memory system, with hidden potential that has not been widely tapped or known.
INTEL uses larger cache for a few reasons but not limited to these...
[1] INTEL processor has more real estate for cache due to more refined lithographical fab tech (eg. 65nm or coming 45nm)
[2] INTEL has potential bottleneck issues with the FSB. more cache means, the cpu doesn't have to use the FSB pipe as much. AMD doesn't have the FSB issue. INTEL took a practical approach, but may be likely to remove the FSB design in near future.
There is a so called 'diminishing margin (or return)' with cache. There will be a time adding more cache will yield little to no tangible performance gain. You can't exactly choose the amount of cache to have. It's pre-determined, hence shouldn't be a major purchasing factor. Generally, more cache is better and the makers will make you payyyyyyyy...
In short, the number of CPU Cores, Frequency and amount of RAM are much more important factors to consider than Cache.
In a funny way, installing more RAM slows the 'aging process' for your computer, say.. in the time frame of 5 years.
If you're planning to use Microsoft VISTA, installing 4GB of RAM is preferred over 2GB. Many latest games demand larger memory footprint.
Under a 2GB system, assuming the VISTA OS will hug 1GB of RAM for itself, that leaves only 1GB for Crysis or Call of Duty 4.
More RAM cuts down on the game load time, and that's how i like my games to be.
-Keep up the good work, thanks again for the data
-
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