Which Memory Clock Speed Is Most Suitable?
The Pentium D 805 works with a front-side-bus clock rate of 133 MHz (533 QDR). Thus, the design of the chipset dictates a maximum memory clock speed of DDR2-533. But overclocking the front side bus also raised memory clock rates; the actual memory clock rate that results from increasing the FSB clock rate may be calculated using a memory multiplier value. Typical Intel platform memory multipliers vary from 2.0 up to 4.0, and may be set as such. Because our overclocking starts from a very low FSB clock speed, a special set of circumstances emerges for the memory multiplier. Namely, for an FSB clock set between 133 MHz and 148 MHz, the only valid memory multiplier values are 3.0 and 4.0 - lower values make no sense.
|133 - 148
|DDR2-400 up to 444
|133 - 148
|DDR2-533 up to 592
|149 - 266
|DDR2-298 up to 533
|149 - 266
|DDR2-396 up to 710
|149 - 266
|DDR2-447 up to 800
|149 - 266
|DDR2-496 up to 888
|149 - 266
|DDR2-596 up to 1066
We assume a multiplier of 4.0 is set, which raises memory clock rates for DDR2-533 for FSB clock rates of 133 MHz to the value consistent with DDR2-667, when the FSB clock is raised to 166 MHz. After that, as you increase the FSB clock stepwise up to 200 MHz, you'll also increase the memory speed up to DDR2-800. If you continue to increase FSB clock rates, you'll also set memory clock rates significantly higher as well.
Some motherboard vendors don't lay out their products to use very fast DDR2-1066 RAM; the reasons for this have to do with the components they choose to populate their boards. These must be of higher quality to deliver clean signals to memory at such high speeds, which makes motherboards more expensive. Even printed circuit board designs play a significant role: data lines designed to run at 500 MHz can be placed very close to one another with lengths of up to almost 4 inches (10 cm). A bad design can cause capacitance build-ups and resonance to develop among circuits, which in turn can cause instability or crashes when clock rates are cranked up.
At FSB clock rates below 149 MHz, memory multipliers lower than 3.0 are not available, because they make no sense in terms of the performance they deliver. With an FSB clock rate of 133 MHz, for example, a 2.0 multiplier produces memory speeds of only DDR2-266.
The various memory multiplier values available in the BIOS vary by motherboard vendor. The 4.0 value isn't always selectable, so buying the wrong motherboard can lead to performance degradation. In most cases, vendors refer to a memory multiplier of 4.0 as "Native DDR2-800."
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I am quite interested in your post regarding the D 805. Considering that it is now available for around $60.00 (03/20/09), it still sounds like a steal. We just upgraded our Adobe CS2 software to the new CS4 Master Suite, which caused the need for a graphics card upgrade. We have an nVidia GeForce GTX 260, but haven't installed it because our computer is a HP Media Center PCm7350n computers each with a 2.8 GHz CPU on a ASUS P5LP-LE mobo. Your article seemed to imply that there is software available that might adjust the clock from inside windows and we are wondering if it can on that mobo or if we will have to get a different mobo. If so, we are wondering what might be our most cost effective but stable options. We are certainly going to need a new power supply for the GTX 260, which requires 525 Watts. We are looking at just putting in PC Power & Cooling’s, Silencer 610 EPS12V power supplyand letting it go at that, but we are also thinking about upgrading the CPU and mobo if necessary.Reply
Of course, we would like to keep the cost down as much as possible.
We have no idea where the best bang for the buck will be. For us a stable system is more important than blazing speed. Thus, the HP's worked fine for what we originally got them for; it’s just that our graphics and video production software are forcing upgrades in speed and power.
The D850 chip sounds incredible and the power supply we already have to get will handle overclocking that chip. It even sounds like that chip will work in the existing mobo if we can find a way to change the clock speed from inside windows instead of from the BIOS. HP BIOS does not allow adjusting the clock speed in the BIOS but can't BIOS just be changed as well; isn't it just an EPROM?
Anyway, even if we opt for changing out the mobo for another case compatible Asus mobo, we still have to answer the question of which board and chip combination will give us the most stable service for the least cost.
Any ideas that might help us plan the most appropriate upgrade and the least cost?
TniasAny ideas that might help us plan the most appropriate upgrade and the least cost?Reply
With the price of components that you need to make this run stable, and the amount of electricity that this would use, a cheap Core 2 and motherboard and DDR2 memory would cost you less in the long run.
Intel Pentium Dual Core E5200
Kingston DDR2 2x2GB 800MHz
This should cost less than $200.
4 year old thread!Reply
11206355 said:4 year old thread!
no hate pl0x