Please help me pick a board for a Q6700

[JHFerry]

Crap, I just realized the FSB of that CPU was 1333. Will that 1066 Ram work with it? The only Ram that fast is DDR3 anyway right?

My options would be return or use it until I can afford DDR3.

[ctal]

Originally Posted by JHFerry

Crap, I just realized the FSB of that CPU was 1333. Will that 1066 Ram work with it? The only Ram that fast is DDR3 anyway right?

My options would be return or use it until I can afford DDR3.

No problem at all with the 1066 RAM.

What is misleading you is Intel's confusing "quad pumped fsb" terminology. Actually, when you have a 1333MHz cpu on a 1333MHz front side bus, NOTHING is really being clocked at 1333MHz. The stuff inside the cpu is running at a much higher rate, of course, like 2.5 or 3GHz or so depending on the cpu. Everything outside of the cpu, including the fsb, the memory, the northbridge chip, and all other busses and devices, is running off of clocks that are much slower than 1333MHz.

The explanation of that is the "quad pumped" business.

First, understand that a clock signal is a square wave, meaning it is at a high voltage for half of its period, and at a low voltage for the other half. The transition from low to high is referred to as a "leading edge," or equivalently a "positive-going edge," and the high to low transition is referred to as a trailing or negative-going edge.

There are actually two clocks going into the cpu, and also clocking the fsb (and the northbridge chip, which like the cpu is connected to the fsb). For a 1333MHz fsb, each of those clocks is at a frequency of 1333/4 = 333MHz. That (333MHz) is the "real" speed of the fsb clocks, meaning that if you measured one clock period of one of the two clocks (from one positive-going edge to the next positive-going edge, or from one negative-going edge to the next negative-going edge), that time would correspond to 333MHz.

The two clocks are "phased" 90 degrees apart, so that the positive-going edge of one clock occurs one-quarter of a clock period after the positive-going edge of the other clock. The cpu is designed to respond to both edges (positive and negative) of both clocks. So for a single clock period, there are 4 edges that can trigger action (a positive-going edge and a negative-going edge of each of two clocks). So Intel refers to the fsb as a 1333MHz fsb (333MHz x the 4 edges).

The reason for that scheme is that in effect the cpu and northbridge are being clocked at 1333MHz, without having to actually distribute within the mobo a clock signal at that high a frequency, which would be difficult or impossible to do over any significant physical distance, without severely degrading the waveform quality.

DDR memory (and DDR2 and DDR3) use both edges of a single clock signal. So without any ratio adjustments a 1333MHz fsb corresponds to a memory speed of 667MHz (e.g., DDR2-667), equal to the 333MHz fsb clock rate x 2 (due to the memory operating off of both edges of the clock signal). And you can, in fact, use DDR2-667 with a 1333MHz fsb with no problem, assuming the bios is designed to accommodate it. With your DDR2-1066, then the mobo has to be set (in the bios) to clock the memory faster than the fsb (defining the fsb speed in non-quad pumped terms), with something like a 1.6 ratio (1066/667), if you don't overclock (and a lower ratio if you do overclock, to keep the memory at or near DDR2-1066 speed).

The internal cpu clock rate is equal to the fsb rate (non-quad pumped definition, in this case 333MHz) times the "multiplier." So an E8400, which is spec'd as a 3GHz (3000MHz) cpu, has a multiplier of 9 (9 x 333 = 3000).

If you overclock the cpu, you do that by raising the fsb rate in the bios settings. In this case, you might raise the 333MHz fsb rate (non-quad pumped terminology) to say 400MHz. That would result in the memory running at DDR2-800 speed if the memory-to-fsb ratio is set to 1:1 (400 x 2, because it responds to both edges of the clock) , so you would want to set the ratio to something like 1.33 (1066/800). If you overclock higher than that, the ratio should be lowered further.

As I said in one of my earlier posts, the idea with overclocking is to maximize internal cpu speed, while still running the memory at or near its specified rate, and while not running the fsb (whose rate is the internal cpu speed divided by the cpu multiplier) faster than the mobo is capable of.

-- Al

[JHFerry]

holy crap dude, nice answer

[JHFerry]

Well I got the system up and running, everything seems to be running fine. Only thing is everytime I shutdown windows the Abit board keeps power to the USB ports. Hope there is a way to change that in the bios.

[ctal]

Glad you got it up and running ok.

Take a look at the bottom of page 2-19 of the manual. The bios settings for "ACPI Suspend Type" and "Resume by USB for S3" appear to be defaulted to allow usb devices to wake the system from a suspend-to-ram state (which is probably relevant mainly to laptops). So the system presumably keeps power applied to the usb ports to allow that to happen. I'd guess that if you set "Resume by USB for S3" to disabled, the usb ports would be powered down with system shutdown.

Regards,
-- Al

[JHFerry]

Al, I posted this on the Abit boards and they didnt notice this. I have not been able to try it out yet but thanks for all the help.