Core Duo Laptops and stock Memory

I am looking at a couple different laptops. All of which have the Intel Core Duo 2.0Ghz with 667MHz front side bus. What I am noticing though is that all the machines come with DDR2 533. Now my understanding is that DDR2 533 is 533MHz. When you go to sites like Crucial or Satech they suggest the memory you use to be DDR2 667. This makes more sense to me since the front side bus is 667MHz. Obviously it works or people would be complaining left and right, but is there a performance loss or any other effects from running DDR2 533 instead of 667?


Thanks.

 

I believe the RAM speed will remain at 533. In reality, 533mhz isn't TOO much of a lower speed at 667.

Of course I could be wrong.

 

I am using a machine with a Core Duo 667MHz FSB and DDR2-533 memory. It doesn't have a large effect on performance, perhaps a few percent in benchmarks. See the HP dv8000t review here:
http://www.notebookreview.com/default.asp?newsID=3010

I would recommend going with DDR2-667. If it is not offered by the vendor, get the machine with the base memory and upgrade yourself.

 

I am sure if I mix and match 533/667 ram it will work (although that is generally a bad idea) but will all 667mhz SO-DIMMs be better/faster then 533mhz SO-DIMMs?

What I really would like to know is what exactly is going on when you run 533mhz ram in a 667mhz system. In the past, this has not worked at all. That is why this is a weird issue for me.

Thanks again.

 

Chaz,

One of the machines I am looking at has 2GB of 533 DDR2 in it already and the price is pretty nice.


This is what I am considering:
http://www.newegg.com/Product/Product.asp?Item=N82E16834115239

Thanks.

 

The FSB really dosent mean anything for the memory speed. I mean P4 systems with 800mhz FSB or 1066mhz FSB's run 533 and 667 ram. They are just the ram speeds that most intel chipsets support. Most today can run both 533 and 667. Now is 667 better than 533. Yes, its faster, so its better, obviously. Now will it make a huge difference in every day computing? Likley not unless you mind word or your browser taking an extra half second to open, or mabey even less. Now if you do heavy gaming or video editing, 667 would have its advantages over 533.

 

The question is even if you use 667 memory will it run at that speed? My guess is no. My notebook has 667fsb and came with 533memory. I think it just uses a divider that runs the memory at 533 for whatever reason. I don't think putting 667 memory will mean that it will actually run the memory at 667.

 

I read somewhere that Sony's bios(the one for core duo of course) limits the ram speed to 533MHZ.

 

Unless you have all 667mhz you might as well have none. Now, if you happen to think you might be upgrading the other stick later, you should go ahead and get a 667 now.

Talking about 533mhz to 667mhz you aren't going to see some huge blazing difference, but it will be there if all your ram is 667mhz. It's all the small things that add up to make a big thing.

 

Thanks all for your replies. So far this information has been great.

 

For Intel based machines at least, having your memory speed match your FSB speed is not as important as you'd think. Remember, your CPU doesn't communicate directly with your RAM; it sends data to/from your Northbridge memory controller across the FSB, which in turn forwards it to/from system RAM.

As to why most Core Duo machines ship with 533Mhz RAM, it's simple. 667Mhz RAM costs more than the 533Mhz DIMMs, and the increased latencies for the higher speed RAM cancel out the gain from increased bandwidth. As such, it's not worth the expense.

I'm pretty sure that you can mix and match 533Mhz and 667Mhz RAM, and both DIMMs will run at the lower speed. So if you're adding to an existing 533 DIMM save your cash and buy another 533.