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Couple questions

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sandrock

Member
Joined
Jul 9, 2003
Location
Green Bay, WI
1) How does raising the FSB affect the PCI and AGP slots. I hear people talking about how it can raise the PCI speed and kill your devices, elaborate on this please? How can it be prevented?

2) With my current setup below, I'm running 200x11.5 @ 1.9v, if possible, I'd like to reach 216 fsb. I hit a wall at around 205. Will increasing the chipset voltage help me reach higher fsb speeds?
 
The pci/agp speeds on your motherboard are locked at 33 and 66 mhz respectively because you have the nforce2 chipset, so you've got nothing to worry about.

To get a higher fsb, raise your vdimm to 2.8 or 2.9v, relax your memory timings., and possibly raise the chipset voltage- but beware overheating your northbridge and/or southbridge chips. I've got your ram, a A7N8X mobo (same chipset) and I'm running my bh-5 at 2-3-3-11 at 2.9v, 10*220 (sig's outdated), Prime stable.
 
sandrock said:
1) How does raising the FSB affect the PCI and AGP slots. I hear people talking about how it can raise the PCI speed and kill your devices, elaborate on this please?

This issue affects only VIA chipset boards such as the KT333/KT400/KT400A/KT600 boards. These chipsets have this problem because the PCI/AGP and onboard controllers such as the harddrive are all run off of a single "timing" source based on the FSB clock. As FSB speed increases the "divider" used to produce the other clocks such as PCI get OC'd also because of the common source.

For example the KT400 chipsets have a 1/5 divider based on the FSB. At max "supported" speed of 166 the PCI clock is set to 166 / 5 = 33.2 Mhz PCI clock which is the Intel spec for PCI speed.

The KT600 has a 1/6 divider so at its max "supported" FSB of 200 you have 200 / 6 = 33.3 Mhz

When you OC to 220 Mhz FSB on the KT600 you get 220 / 6 = 36.6 Mhz which is pushing the PCI / AGP and on board controllers to the max. Hard drive corruption is common at speeds above 36 Mhz on the PCI bus.

nForce2 boards, nForce3 boards and many newer Intel boards have done away with a common FSB clock for everything and instead have moved to seperate clocks for each device. This allows FSB clocks that only hit a ceiling caused by the CPU and not seperate devices like PCI, AGP cards, harddrives or Ram.

Im not sure why VIA has stayed with the single timing source but it definetly puts them in second place with the OCing crowd. Most likely it is because VIA really only wants OEM business with folks like Dell who never OC a system they sell. In that case the VIA chipsets are reliable and work well.


:cool:
 
Unfortunately nForce3 boards will not have a PCI lock it seems.

But nForce2s do. Abit NF7-S is an nForce2 so you got nothing to worry about.

There is something called a PCI lock and nForce2s have it and VIA mobos do not.

Increasing the FSB changes the speed of the whole motherboard and everything connected to it unless the mobo has a PCI lock. PCI lock is good because it saves your other components from the negative effects of overclocking.

VIA mobos use a divider.

First of all FSB is more important than MHz.
MHz is FSB x multiplier but the idea is to have the highest FSB possible. Without a PCI lock, that may not be an option. This is why:
Lets’ say VIA mobo has a /4 divider for 133 FSB and up, then a /5 divider kicks in for 166 FSB and up.

That also means with overclocking to say, 180 FSB: 180 /5 = 36
...and then overclocking even more: 190 /5=38.

38. That’s 15% out of specs your hard drive and sound cards and everything connected to the mobo is running out of specs.

You go further than that and you’ll be entering into hard drive scrambling territory... unless you have a PCI lock which nForce2 does and VIA does not.
 
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