How much does memory speed matter?

[Cyde Weys]

I'm pricing a new system based around a dual core 64-bit AMD AM2 socket
processor and all of the motherboards support DDR2 800. Is it really
necessary to get memory that fast? DDR2 800 memory is a bit more
expensive than, say, DDR2 667. Does the performance gain justify the
increased cost? Is there any performance gain, or is the bottleneck
somewhere else in the system other than the memory bus?

 

[paulmd]

I'm pricing a new system based around a dual core 64-bit AMD AM2 socket
processor and all of the motherboards support DDR2 800. Is it really
necessary to get memory that fast? DDR2 800 memory is a bit more
expensive than, say, DDR2 667. Does the performance gain justify the
increased cost? Is there any performance gain, or is the bottleneck
somewhere else in the system other than the memory bus?

It is important to maacth the memory speed, with the front side bus of
the processor. If the memory is too slow, either it will be a
performance drag, or it will try to overclock the RAM.

Memory too fast for the processor is indeed a waste of money.

 

[kony]

I'm pricing a new system based around a dual core 64-bit AMD AM2 socket
processor and all of the motherboards support DDR2 800. Is it really
necessary to get memory that fast? DDR2 800 memory is a bit more
expensive than, say, DDR2 667. Does the performance gain justify the
increased cost?

Does the performance gain of buying a new system at all
justify the increased cost over (not buying one)?

We can't answer this for you, as always the higher the
performance in any given era, the higher the premium you'll
pay to get it... unless overclocking but then it's the time
to ensure it works right/well/etc, instead of the $, spent.

Generally, yes DDR2-800 is worth having.

Is there any performance gain, or is the bottleneck
somewhere else in the system other than the memory bus?

As always, it will depend on the task. Same goes for rated
timings rather than bus speed rating. If anything the
DDR2-800 seems the best choice because it will have a longer
lifespan, more potential to be reusable.

 

[Paul]

I'm pricing a new system based around a dual core 64-bit AMD AM2 socket
processor and all of the motherboards support DDR2 800. Is it really
necessary to get memory that fast? DDR2 800 memory is a bit more
expensive than, say, DDR2 667. Does the performance gain justify the
increased cost? Is there any performance gain, or is the bottleneck
somewhere else in the system other than the memory bus?

If you can figure out what exact settings they were using, there
are some benchmarks here. I suspect their processor wasn't kept
at the same frequency, which would bias the results.

Photoshop CS (bottom of page) - some improvement
http://www.tomshardware.com/2006/05/23/amd_reinvents_itself/page37.html

Gaming, F.E.A.R - not as much
http://www.tomshardware.com/2006/05/23/amd_reinvents_itself/page29.html

Expensive memory is a pretty hard way to buy performance.
Overclocking is the cheapest way.

Paul

 

[Bazzer Smith]

I'm pricing a new system based around a dual core 64-bit AMD AM2 socket
processor and all of the motherboards support DDR2 800. Is it really
necessary to get memory that fast? DDR2 800 memory is a bit more
expensive than, say, DDR2 667. Does the performance gain justify the
increased cost? Is there any performance gain, or is the bottleneck
somewhere else in the system other than the memory bus?

I am not an expert on such matters but the 800 is 20% higher than 667.
So the most improvement you could ever expect to see is 20% if the
application
was 100% 'memory speed bound'. When that happens is any bodies guess :O)

I would say it is more important to have 'more memory than you need' rather
than
faster memory, I mean if you have very fast memory and the system is
accessing your
*mechanical* hard drive the bottle neck would be the hard drive?
Also you will have your L1 and L2 caches which will be much faster than your
memory
bus.

Depends what you are doing though, but in a 'blind test' I doubt you could
tell the difference
between the two memory types!

Depends what the price differentials are I guess, resale value might also be
a consideration.

 

[ElJerid]

I'm pricing a new system based around a dual core 64-bit AMD AM2 socket
processor and all of the motherboards support DDR2 800. Is it really
necessary to get memory that fast? DDR2 800 memory is a bit more
expensive than, say, DDR2 667. Does the performance gain justify the
increased cost? Is there any performance gain, or is the bottleneck
somewhere else in the system other than the memory bus?

As always, it all depends of the application. If you're doing office work,
or internetting, then most parts of your computer are oversized. But if
you're a fanatic gamer, or a video editer, or working with huge Photoshop
files, then yes, every high-performance component will be welcome !

 

[Mike Walsh]

Memory speed is usually not a bottleneck. Such things as processor speed, disk speed, amount of system memory and cache are more important for overall performance. DDR2 667 is adequate for the fastest processors. If you will be running applications that make full use of both processor cores (effectively doubling memory bandwidth requirements) then you should use DDR2 800.