I am designing my first rig.
So far I am looking at the Q9550, a GTX9800, 8 Gig Ram DDR2 (800 or 1333 mhz I am not sure yet which), Vista 64...

My real question here is about the FSB attached to the mobo - I understand that most FSB's these days are 64 bit buswidth (right??), I am wondering if anyone knows of mobo's that are FSB of 128 bit budswith and also if does anyone know if my Q9550 cpu would be compatible with / be able to make use of a mobo with a 128 bit FSB?

(The Q9550 has 1333mhz for FSB in the specs).

I figure I have 8gig ram so I want to make the exchange between the ram and cpu as accomodating as possible. This begs the next question which is what mhz for the DDR2, 800 or 1333??

Also in terms of backside buses, are there mobo's that have bigger budswidth for those aswell as the FSB buswidth being 128 bit etc? Am trying to completely avoid bottlenecks in data exchange here, please offer a suggestion or comment (am really stumped here)!

forgot to say that I'm not fussed about the cost (using the Q9550 as the CPU) ie. I want the optimal ram, mobo setup to cater for that cpu and it is really hard trying to decide!

Using the Q9550 as your CPU limits you to socket 775 motherboards with all the hardware limitations that go along with the PC class of computers.

The backside bus is wholly contained inside the CPU die and has nothing to do with the motherboard.

Thanks WR2, what would be the best 775 socket mobo adn ram configuration then? and can you get 128 bit fsb's on 775 socket mobo's? when you say hware limitation what do you mean ie. do you mean my cpu wont interface well with a 128 bit fsb or that i cant get a 128 bit fsb on a 775 mobo etc?

What is your overclocking target with the Q9550?
128bit FSB? Are you trying to build a scientific workstation on the cheap?

ha yeah i guess... im not trying to overclock i am trying to build a stock operated system (ie. one that i dont have to manipulate) that is going to totally (or as best possible) avoid bottlenecks between cpu and ram. i dont care about cost of ram or cost of mothreboard as long as the two are faciliting the purpose (ie. not future upgrades or ocing, just kick ass load times/ multitaksing using a Q9550) - i don't think it's that complicated really, just need someone who knows what they're on about to give me an ideal ram/ motherboard scenario for my Q9550, is that so hard???

strike that... ideal ram/ motherboard featuring ideal fsb capability in terms of buswidth

single channel is 64 bit. Pretty much all motherboards have dual channel memory controller so if You put ram in pairs and use dual channel it is 128 bit wide. At least that is what I understand, might be wrong.

Yep found confirmation on wikipedia-
Dual-channel architecture describes a technology that doubles data throughput from RAM to the memory controller. Dual-channel-enabled memory controllers utilize two 64-bit data channels, resulting in a total bandwidth of 128-bits, to move data from RAM to the CPU.
http://en.wikipedia.org/wiki/Dual-channel_architecture

clap clap clap,
What about the best ram configuration
ie. 4 gig vs. 8 gig, 667 vs 800 vs 1333mhz, DDR2 vs. DDR3,
(remember cost of mobo and ram are of no consideration based on the Q9550 as CPU platform)
we're almost there now...

ainairsseems (thanks for your comments so far, your two notches above 95% of the people on here in my book)

I've read some of your other posts and you seem to be obsessing about a 128bit FSB for some reason.
Don't fool yourself into thinking a RAM dual channel 64bit FSB is actually a 128bit FSB. It' not. You have to think about the CPU side of the bus as well

Also you appear to be confused about FSB bandwidth's function in providing "kick ass load times/ multitaksing". That may be why you seem to be confusing others around here.

All 1333Mhz CPUs have a FSB bandwidth of 10666 MB/s. Two cores or four cores - its all 10666 MB/s.
The 2.5Ghz Q9300 and 3.0Ghz QX9650 all have the same FSB bandwidth and yet the QX9650 "kicks ass" faster?
FSB bandwidth is a function of the FSB speed. More speed=more bandwidth.
To increase the bandwidth (which you appear to be asking when you say "avoid bottlenecks in data exchange" ) you need to increase the FSB speed. That's called overclocking. Besides generating "wider" bandwidth a side benefit is that tasks get completed faster (as in kicking ass). Ok, actually its the main benefit and the higher bandwidth is just a bonus.

For example if you overclock the Q9300 to 3Ghz you'd raise the FSB to 400Mhz (1600Mhz quad pumped).
400*4*8=12800 MB/s of FSB bandwidth. Mmmmmmmmm! More bandwidth! Faster loading, execution and multi-tasking (but most of the increase not provided by the higher bandwidth).

To find optimum RAM? How to match the CPU bandwidth with RAM bandwidth? Have you ever wondered why RAM has TWO names?
As in DDR2 667 PC2 5400, DDR2 800 PC2 6400, DDR2 1066 PC2 8500 and DDR3 1333 PC3 10666?
The DDR part indicates data transfers per second (in millions); 677 million data transfers, etc.
The PC part indicates single channel bandwidth - as in PC2 5400=5400 Mb/s, PC2 6400=6400 Mb/s
Or PC3 10666 DDR3 1333? PC3 12800 DDR3 1600? Notice anything familiar? 1333/10666 & 1600/12800?

So what happens if you don't use optimum RAM? Not too much changes. Say you're using DDR2 800 PC2 6400 RAM?
The actual performance is very close - only a few percentage points difference which is why so many people recommend non-optimum RAM. A Q9300 1333Mhz FSB with DDR3 1333 PC3 10666 RAM running at 2.5Ghz will get its butt kicked soundly by a 3.0Ghz Q9300 1600FSB with DDR2 800 PC2 6400 RAM. Same principal applies to all CPUs.

2GB vs 4GB vs 8GB; The RAM's primary purpose is to to keep the L2 cache filled with data and instructions (as the L2 cache keeps the L1 cache filled with data/instructions for actual execution tasks). That's one reason why doubling your RAM from 2GB to 4GB and again to 8GB doesnt double your actual performance. Again a faster clocked CPU (3.0Ghz) with 2GB will almost always kick ass over a slower clocked CPU (2.5Ghz) with 4GB (or 8GB for that matter).
And we havent even started talking about CAS latency and Command Data Rates

Bottom line - CPU frequency changes have a far larger impact on performance than FSB bandwidth, RAM speed or amount of RAM installed.

Always remember - todays $3000 worth of PC performance can be had for $1500 in 18 months.
My opinion is that you should set a comfortable fixed budget and let the forum members help you build a fully balanced, bang for your bux, kick ass system.
Set the budget, tell people how you intend to use the computer, the types of tasks you will use it for and what's important to you.

Thanks WR2, appreciate the explanation, sounds like I need to learn overclocking to get that really amazing performance. Just so you know, I'm looking at 1500-$2200 as an overall spend. I'll be using it so internet 7 windows, some finance comparison software, downloading several thingsa and listening to music all at the same time. I might get a copyof Call of Duty 4 (instead of buying a PS3) and play multiplayer on that online, and from what you've said I'm much more interested in learning overclocking techniques now too. Any suggestions based around this info??

Just an early first cut based on your budget being for a complete system including peripherals like monitor, keyboard/mouse, speakers, etc.
I used the http://www.scorptec.com.au website for current pricing.
If you have a favorite e-tailer or store you'd prefer to use go ahead and mention that.
And if you have any exisiting kit you'd like to move over to the new system mention that as well - speakers, things of that nature.
For personal preferences do you prefer quiet or understated systems?
Or a bit more flash as in transparent case windows and LED lights?

For the core tower system:
Asus P5K-EPU $160
Xeon 3230 Quad 2.66Ghz $385 (Same as C2Q Q9450 2.66Ghz - $449)
(initial overclock goal = 3.2Ghz 400FSB for CPU power equal to $1750 QX9770 3.2Ghz)
Crucial Ballistix 4GB DDR2 800 PC2-6400 CAS4 $160
XFX GF 8800GT 512MB $299
WD WD6400AAKS 640GB 7200 16mb SATA3 $119
Lite-On DH-20A3S DVD Burner SATA $35
Arctic Cooling Freezer 7 Pro CPU Cooler $45
Cooler Master RC-690 case - $99.00
Corsair 550VX PSU - $149.00
$1451

Peripherals
Samsung 2253LW 22" LCD 1680x1050 $329
Keyboard/Mouse = Logitech Cordless MX3200 $129.00
Altec Lansing VS2421 Speakers $79
Vista Home Premium 64bit SP1 $175
$712

Hi WR2, thankyou for that suggestion, in terms of understated/ quiet etc, I wouldn't mind something a bit flashy, if looks like more like a spaceship it might help explain to my g'friend where the cash went, in terms of migrating old kit over - I've got nothing worth bringing over, this rig is really a full departure from my existing and annoyingly slow computer, just wondering about the xeon, what's the reason/logic behind that recomendation (don't want sound rude, it's just that I don't understand the xeon's benefits)?