FSB Confusion...

Hello everyone.

First, let me apolgize if this thread is a duplication of efforts already undeway in a different thread. Also, apologies if I'm in the wrong forum altogether.

I've been out of the system-builder arena for a few years now, and my son is taking a page from his old man and really wants to get into computer gaming. Being the "gamer dad" that I am, how can I say no to that?! However, when pricing out some system to build for him for his up-coming December birthday, I'm at a bit of an impasse when developing a system. Here's what I do know, however: I'd like to take advantage of the Intel Core 2 Duo processors. I was amazed at the price vs. performance ratio! So I went online and found this: the E6750 Core 2 Duo processor at 2.66Ghz for less than $200 bucks. Seems like a great place to start.

However...

I'm very confused with the FSB numbers. When I look at "pre-fabbed" systems with Core 2 Duos, it seems they all use 800Mhz DDR2 memory. I had always (perhaps incorrectly) assumed that if the processor FSB indicator was 1333Mhz, I need 1333Mhz memory. Is that not right? Many of the Intel P35 motherboards I am looking at say they support 800/1066/1333 FSB's. I guess what I am asking is: what memory do I use? Clearly, 800Mhz chips are the way to go, at least on the cheap. But am I robbing his PC of performance by doing so? Would it even work? And for that matter, if the board supports 1066 FSB (in addition to the others) should I go to DDR2 1066? Is 1333 even worth the investment? Talk about confusing!

And sort of on top of this, if I were to disregard the P35 platform, is the nVidia 680i platform worth investing in with the same processor?

Thanks for all the insight in advance,

d

Its the difference between effective and actual. Most C2Ds use a 1066MHz EFFECTIVE FSB. As Grimmy pointed out, don't forget that the FSB is "quad pumped." (meaning that Intel has figured out how to send 4 bits of info per clock cycle.) If you devide 1066MHz by 4, you get the "real" clock speed of 266. DDR memory is Double this speed, so you really only need DDR2 533MHz ram to have things work the way they should. You can put faster ram in there, but it will default to the lower speed. (you can make it run at DDR2-800MHz, but that isn't much faster.) If you buy one of the new 1333MHz CPUs, you could do the math yourself. 1333/4=333MHz. 333MHz * 2 = 666MHz. The 1333MHz CPUs need at least DDR2-667 ram to work without any ram problems.

As a side note, some people like to buy the DDR2-800MHz ram and put them in DDR2-533 systems. This allows them to tighten the timings on the ram a lot, making the system faster.

1066 are the best chips

the 6420 is a great chip since the oc will bring you too the 1500-1600 sweet spot for fsb and you can use ddr800 at 1:1

the q6600 is the best choice

stay away from the stripped down 800fsb chips, these are for cheap mobos - get a good mobo a p35-R (ichpr =raid)

gigybyte is nice asus is better and alot easier to oc

Let me just clarify: I'm not in to overlocking. I just want to make sure that this 1333 Mhz FSB chip will run as expected with DDR2-800 RAM.

If I'm reading all this right, it will, correct?

I remember reading a recent article and the gist of it was that the memory numbers (DDR2-1066, DDR2-1333, etc) is reflective of the effective speed and also how they correspond with the front side bus of the processor. So for all intents and purposes and for Joe Average putting a machine together, if he's selected a C2D with a 1066 fsb it is safe to select memory advertised as 1066. And, for Joe Average who is not overclocking and not wanting to have to worry about adjusting dividers, then matching the fsb bus of the processor with memory advertised to run the same speed is the easy way to go.

I didn't know Intel drove trains too... must save them on shipping I guess.

-scratch my question... I even confused myself- . o O (lack of sleep)

Since ya quoted my edit, what I really meant by that, is most people (average Joe or below) is going to look at the bigger number. Just like when people were freaking out wondering why a 1.8ghz C2D cpu did quite better then the old P4 3.2ghz CPU. It's the numbers that sells the product, is all I'm saying.

After reading some reviews on the DDR2-1066, it seems to be good fast memory. But for the cost? Blah.. doesn't really justify it now, just like when DDR2-800 was expensive.

See, that's where I'm coming from: will I have to fiddle with BIOS settings if I get the E6750 and some DDR2-800? And again, is there performance to be had with using 1066 over 800, or 1333 over any of those?

That's all I'm really asking: consider this scenario: I have a board that supports the new 1333FSB processors. If I had 3 sets of memory at all those speeds, is there an advantage to one over the others? If I go with a "mismatch" set (i.e. the 1066 or 800) will the bios of the board detect that? Am I subjecting myself to performance loss by doing so? This is what I need to know.

And extra bonus question: do I need to concern myself with memory timings. Example: right now if I shop for memory, there's like, 5 different kinds of the same brand/speed of DDR memroy with set timings. Will any ol' timings do.

Help!

lghtmup98 got it basically right. The difference however, between all the memory speeds, is neglible due to the C2D's big L2 cache. You shouldnt get better than 667 or 800 MHZ RAM unless your building a super high end system, but be aware 667 is the minimum for that processor. As for the 680i platform, don't bother unless your going to be putting in two high end cards. The P35 or 650i would do you fine.

if you buy 667 make sure it runs 3-3-3-5

if your not overclocking and you running 1066 then IE above is right - as long as you get good ddr667

dont get 5-5-5-15 ddr667 that is reject ram

usually ddr800 4-4-3-8 (which is very low in clost) will run 3-3-3-8 or 3-4-3-8

if you buy 1066 ram you need 4-5-4-12 to match the 3-3-3-8 bandwidth of the 667

they approximate