noob question about selecting Memory

[leeland]

OK going to be building a new rig (first in awhile), and I am a little lost on these memory speeds...

Back when I last built a rig it seems like the FSB speeds were only one speed. Now when I review new motherboards they have multiple speeds and that is confusing to me.

For Instance P5B Deluxe has a FSB listed of 1066/800 Mhz...

So that would take PC26400 or PC28500 speed RAM correct?

Wouldn't I by default want to take the faster speed RAM? I would think so but I see people getting the PC26400 speed RAM for their builds...

I know this probably sounds like a really stupid question...if anyone can give me a little explination I would really appreciate it.


Thanks,

Leeland

 

[Tarrant64]

Originally posted by: leeland
OK going to be building a new rig (first in awhile), and I am a little lost on these memory speeds...

Back when I last built a rig it seems like the FSB speeds were only one speed. Now when I review new motherboards they have multiple speeds and that is confusing to me.

For Instance P5B Deluxe has a FSB listed of 1066/800 Mhz...

So that would take PC26400 or PC28500 speed RAM correct?

Wouldn't I by default want to take the faster speed RAM? I would think so but I see people getting the PC26400 speed RAM for their builds...

I know this probably sounds like a really stupid question...if anyone can give me a little explination I would really appreciate it.


Thanks,

Leeland

I am thinking those are not typos, and I am not sure you're seeing the meaning behind the different types of memory speeds.
I am looking for a guide on memory...here. But I don't see one. I'll keep looking.


I can't believe I'm going to bitch because there isn't a memory guide on AT. Sticking my shoe in my mouth I am.

 

[JeffreyLebowski]

1066/800 is FSB. Processors like the Core 2 Duo e6300 and above use the 1066MHz FSB. The E4300 and Pentium D's use the 800MHz bus. DDR2 533 (which is actually 266MHzx2) is enough for the e4300 and Pentiums as the bus is quad pumped, meaning it runs at 200MHz x4=800MHz The 1066 for Core 2 Duo e6300 and above is 266MHz x4 =1066(4). When you get RAM faster than that it helps some with latency times and allows more head room for overclocking.

For the price of memory these days, get DDR2 -533 and you will be fine.

 

[leeland]

Originally posted by: JeffreyLebowski
1066/800 is FSB. Processors like the Core 2 Duo e6300 and above use the 1066MHz FSB. The E4300 and Pentium D's use the 800MHz bus. DDR2 533 (which is actually 266MHzx2) is enough for the e4300 and Pentiums as the bus is quad pumped, meaning it runs at 200MHz x4=800MHz The 1066 for Core 2 Duo e6300 and above is 266MHz x4 =1066(4). When you get RAM faster than that it helps some with latency times and allows more head room for overclocking.

For the price of memory these days, get DDR2 -533 and you will be fine.

Thanks for the info Jefferey...however I am still not putting 1 and 1 together.

I realize all the stuff about FSB...the FSB on the E6600 is 1066 which would match up with the Asus MB I listed above which also supports a FSB of 1066 (4x266).

The way I understand it (PLEASE correct me if I am wrong !!!!) is that you want to get memory that is rated to run at the correct FSB speed correct?

This is the part I am a little fuzzy on and making assumptions

So I would want to get PC26400 (800Mhz) or PC28500 (1066 MHZ).

if I got the PC28500 it would run with a divider of 1:1 matching the CPU FSB (Correct???)

However when I look on newegg it lists/recommends to get DDR2 800...

that is just confusing to me because from the little I am understanding that would be slower that what the default FSB would be for the E6600 Chip correct?


I am sure I am totally missing the point here and am way off base so if someone can clear this up I can save some face


Thanks,

Leeland

 

[n7]

Default FSB for C2Ds [excepting E4300/E4400] is 266 Mhz quad pumped (266 x 4 = 1066 MHz)

That means you need RAM running @ 266 MHz for 1:1, which is DDR2-533 (double data rate 266 MHz).

Higher speed RAM would run at a faster speed than the FSB, which does somewhat improve performance, as well as allowing for overclocking w/o RAM becoming the limiting factor.

DDR2-1066 really isn't necessary though unless you like heavily tweaking/clocking, or have money you wish to burn.

 

[leeland]

Originally posted by: n7
Default FSB for C2Ds [excepting E4300/E4400] is 266 Mhz quad pumped (266 x 4 = 1066 MHz)

That means you need RAM running @ 266 MHz for 1:1, which is DDR2-533 (double data rate 266 MHz).

Higher speed RAM would run at a faster speed than the FSB, which does somewhat improve performance, as well as allowing for overclocking w/o RAM becoming the limiting factor.

DDR2-1066 really isn't necessary though unless you like heavily tweaking/clocking, or have money you wish to burn.

I totally found my answer...I wasn't putting my question in the correct context I think...

Link

Basically DDR2 800 will allow me the room I need if and when I do decide to Over clock the system...


It won't hurt anything would it if I left the CPU at stock speed and had a higher speed memory correct?

 

[Roguestar]

Correct. Basically those motherboards are saying they support up to DDR2-1066, but you can run anything down to DDR2-533 on them. Technically anything over DDR2-533 is a waste if you're not overclocking, as it'll all be run at DDR2-533 speeds anyway unless you've changed the FSB and memory speed to overclock. Buying DDR2-800 will mean that if you decide to overclock, you've got no problems bringing the FSB up to 400Mhz without even touching the RAM settings. Otherwise after that you'll need to overclock you RAM; which may involve increasing voltage and decreasing timings.

 

[leeland]

Originally posted by: Roguestar
Correct. Basically those motherboards are saying they support up to DDR2-1066, but you can run anything down to DDR2-533 on them. Technically anything over DDR2-533 is a waste if you're not overclocking, as it'll all be run at DDR2-533 speeds anyway unless you've changed the FSB and memory speed to overclock. Buying DDR2-800 will mean that if you decide to overclock, you've got no problems bringing the FSB up to 400Mhz without even touching the RAM settings. Otherwise after that you'll need to overclock you RAM; which may involve increasing voltage and decreasing timings.

That is what I took away from that website I linked...basically I have up to 400 Mhz for a FSB that I can move to until I have to think about messing with the RAM as far as speeds are concerned.

What happens if you DO NOT overclock and you have faster speed memory vs what the FSB of the CPU is running at? Nothing? That extra speed is just wasted regarding the memory speed/bandwidth?

Put another way, the memory bandwidth would not be 100% utilized until the FSB of the CPU was increased to match the RAM?

It is all starting to make more sense...however one last question.
Question
If you go on Newegg and look up that Asus board...it lists the Recommended Memory as DDR2 800...not DDR3 533. Why would that be? if like you said "you don't plan on overclocking" you should be able to use just DDR2 533 memory to have a 1:1 ratio with the FSB of the CPU.

Thanks again Roguestar...

Leeland

 

[Roguestar]

Basically, if you have DDR2-800 in an unoverclocked standard Core 2 Duo with no settings changed, it is running at DDR2-533. The extra speed is essentially wasted unless you are explicitly taking advantage of it by changing memory:FSB ratio or overclocking the FSB.

About Newegg, they're probably recommending the DDR2-800 because it has a little leeway, or more likely because then people will buy it at a premium instead of looking for the best value item at the specification they actually need .

 

[leeland]

Originally posted by: Roguestar
About Newegg, they're probably recommending the DDR2-800 because it has a little leeway, or more likely because then people will buy it at a premium instead of looking for the best value item at the specification they actually need .

Those Bastards Thanks for the info and clearing it up for me.!!!