Memory frequency question

[soulskorpion]

Hi. Got a quick question: how significant an impact does memory speed have on system performance? I've seen a hell of a lot of articles analysing how memory capacity affects performace, but not really anything on how the actual speed of the memory affects things.

Basically, I'm thinking of getting a DDR2-800 capable motherboard for the system I'm going to be putting together, and I was wondering whether it's actually worth the money or not.

 

[mitch074]

It depends heavily on the memory controller installed;
- Amd integrated memory controllers (AM2 sockets) appreciate very fast timings (the lower the better) and in a certain measure synced CPU interface/memory syncing (ddr2/800 with fast timings would work best with those, but avoid ddr2/667)
- Intel Core2 CPUs are not really influenced by memory speed; cheap ddr2/667 in huge amounts would in fact be better than fast/expensive ddr2/800 in lesser amounts

Now I don't own a ddr2 based system (my X2 is s939) but all the posts/benches I've seen show that current Athlon64 with ddr2/800 work on par with Athlon64 using ddr/400, and that any other ddr2 RAM would in fact slow them down.

If you have a Core2, its unified l2 cache makes fast RAM an unnecessary expenditure except for the very enthusiastic crowd.

 

[soulskorpion]

I am planning on getting an Intel Core 2.

I figure I'm probably going to need a lot of memory in any case, since I'm planning on running virtual machines on it from time to time. With similar amounts of memory, would there really not be any noticeble difference in performance with faster memory?

...mind you, I've just had another look at the prices for memory that I've found, and it's at least $100AUD more expensive to get DDR2-800. I guess I'm going to just have to do the numbers. On that note, are there any benchmarks available anywhere for this? I haven't been able to find any.

 

[mitch074]

on a core2 where you intend to run VMs, you are better off getting ddr2/667, ensuring your Core2 has a lot of l2 cache, and get vast amounts of RAM - the 1-2% absolute performance hit is completely canceled out if you get twice the amount of RAM on such a system.

 

[num_lock_er]

I've a question regarding memory combination. I've an existing 1 stick of 256mb ddr266. Which has a better performance? I will use it in surfing with 5 tabs open while downloading a torrent. I will also use my PC in Wolfenstein ET online and sometimes NBA live.

1. 256mb 1stick existing + 256mb 1stick additional = 512mb total

or

2. 256mb 1 stick existing + 512mb 1stick additional = 768mb total (25$ more)

I'm tight on budget for my existing PC. I'm saving for a new laptop.

Thank you.

Numlock

 

[Mondoman]

Please don't hijack threads to change the subject.
Please don't ask the same question on multiple threads.
Your question has been answered on your original thread.

 

[Mondoman]

It's worthwhile to take a look at various actual tests run on C2D systems. C2Ds are more sensitive to slower latency than were Pentiums, but still much less than AMDs.
Stock FSB on C2Ds is fully saturated at DDR2-533 memory speeds, so without overclocking the FSB, overall performance gains at higher memory speeds are limited, and may actually be negative in some cases for DDR2-667 speeds. Thus, if you have DDR2-667-rated RAM, try running it at both DDR2-800 and DDR2-533 to see if you get improved performance.
C2D CPUs seem to support OCing very well, so consider OCing the FSB to at least 333MHz (1333MHz effective data rate), which will be synchronous with DDR2-667 memory bus speed.

 

[soulskorpion]

Interesting. I didn't realise that bit about the FSB. I'm not intending to overclock any of my components, though.

I'm having a bit of trouble finding benchmarks for memory, though. Lots of reviews for specific brands, but no comparative benchmarks between different frequencies.