DDR2 v DDR3

Ok im sure this hase been discussed before but i didnt find what i was looking for in search.

Im in the market for a new or lightly used laptop. DDR3 is basically standard now but there are a few still out there with DDR2. How much a difference will i feel with DDR2 (4gigs) and a faster processor compared to DDR3 with a slower CPU? Specifically 4gb DDR2 on a 2.26ghz C2D with a 1066mhz FSB 3mb cache vs 4gb DDR3 on a 2.2ghz C2D with a 800mhz FSB 2mb cache.

Thanks.

 

I asked the same question before and the difference shouldn't be that big, atleast thats what they told me.

 

yea i dont know.

Im basically wondering what the limiting factor on speed it. The ram, cpu or FSB.

 

Depending highly on the apps you run:

The limiting factor on performance is usually CPU, RAM (amount, not speed), GPU, FSB.

Cheers!

 

Memory type will never be a bottleneck to any current system. But as DDR2 production stops, its price will increase, so for a new system, I'd consider DDR3 only because of that. Btw new CPUs don't have FSB anymore, but either way, the CPU itself won't be able to take advantage of the full bandwidth provided by DDR2/DDR3 or even FSB/QPI (the new replacement for FSB in Core i3/5/7 CPUs).

 

I agree that memory type is never a bottleneck in most situations, but are you sure about CPU's can't take advantage of RAM's bandwidth?

I've always thought that CPU's were orders of magnitude above their cache's, which are orders of magnitude above the RAM, which are orders of magnitude above the storage subsystem.

Isn't this why RAM has latency? Because it is trying to sync to the much faster CPU it is trying to keep fed with data?

Maybe I need to correct my thinking here? Any help is appreciated.

More info? Links?

Cheers!

 

You are correct. For example, there have been a number of scientific papers written on the subject of cache aware data access. The goal is to stay on the cpu cache as much as possible as opposed to going out to the system memory. The cache is many times faster than main memory.

 

corrected

 

Sorry, you are correct, but what I meant was that neither of these things in the system are usually the bottleneck, so even though you increase bandwidth, such as going from DDR2-667 to DDR3-1333, the difference in performance in any real life situation is within the range of error (negligible performance difference).

 

clock rate for clock rate, refresh timings for refresh timings, if the numbers are the same, the performance will be the same.

The design point of DDR3 is (reduced) power consumption, not improved performance over DDR2.

 

Not every modern CPU is now an i series...for the record.

 

[QUOTEOriginally Posted by tilleroftheearth
The limiting factor on performance is usually HDD, CPU, RAM (amount, not speed), GPU, FSB.[/QUOTE]

Phil, I agree with you that the HD is very important too - but 'work' happens only on a CPU/RAM/GPU combo - never on a HD.

It's true that a HD can be used to make limited resources seem limitless (when you're limited by RAM), but work is never performed on the HD (it can't be), it is only stored there waiting its turn for some free RAM and CPU time to be available so it can be processed too.

A fine distinction, I know, but an important one.

Cheers!

 

As soon as you turn on the computer you're waiting for the HDD. And that's the same for everyone, whether you're on an Atom netbook or Core i7 notebook doesn't matter.

And then when you start up you're work you're waiting for the HDD again.

I know you already know this Tiller but it seems many people ignore their hard drive choice while paying a lot of money for CPU power and amounts of memory they never need.

 

Thanks Phil,

Yes, you're certainly correct too! If you optimize every other aspect of the computer and ignore the storage subsystem - the overall feel will be like a computer from a decade ago - no matter how fast it is at the 'work' part.

I stop upgrading a computer when the individual components are matched/balanced to each other. That computer then is pleasing to work on for a very long time - even if its slower than what is currently available.

On the other hand, when I first buy a new system - no matter how fast it is compared to the old systems - if it is not 'balanced', then I'll prefer to work/use the old systems until the component(s) that are making the new computer 'unbalanced' are fixed.

Yeah, a I'm a little weird; but there is a cadence to computer work that is easily disrupted for me by things as seemingly small/insignificant as an 'unbalanced' computer system.

Cheers!