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Proper pci-e frequency?

C

computater

Weaksauce
Joined
Apr 4, 2006
Messages
65
I remember reading somewhere that the proper pci-e frequency setting in the bios should be 105, whereas nvidia cards need the default 100 or 101. Is this correct?
 
computater said:
I remember reading somewhere that the proper pci-e frequency setting in the bios should be 105, whereas nvidia cards need the default 100 or 101. Is this correct?
Click to expand...

PCI-E = 100MHz
 
on newer Asus MB you leave it on auto as it will scale with your OC. However, other Boards require you to start at 100 and work you way up from there. I devised a formula that worked well with a restricted PG5D1 man it was a horrible board anyway. However I learned that the power factor for that MB is 2.2 which means for every 2.2MHz I increase the FSB I must increase the PCI-E Frequency by 1Mhz. This is a solid formula for that board. However, you must know the power factor for your board. However the P5WD2-2 Pre adjust automatically and if I go manually I will lock up.

This is a bit complicated because I have a P5GD1, 660, with a Corsair 3200C2PT (2-3-3-6 up to 225, 2.5-3-3-6 230 so far at 18x multi). I start off with a PCI express Frequency base of 100 with a FSB base of 200 then work my way up by a factor of 2.2 (for every 2.2 MHz on the FSB you increase your PCI express frequency by 1..

For example:
Your PCI Express Frequency has a base of 100. Your FSB has a base of 200.
If you increase your FSB to 230 then you increased your base by 30 MHz.
Divide that by 2.2 (30/2.2) and you get 13.63.
Round 13.63 up and you have value of 14 for your PCIe Freq.
I add 14 MHz to my PCI Express Frequency (100+14) and get 114 that I put in the bios
114 will be my new PCI express frequency at a FSB of 230.

Again this does not work if your MB is design to do this automatically. And, the 2.2 is for the P5GD1 only...as far as I know to date...
 
Just a question with your formula: does the HTT multi matter or simply the FSB (ie, actually processor mhz or just the fsb)?
 
100mhz is the technical speed for pci-e

however, on some chipsets things work a little funky and setting it to other values can be handy. For example, on 945-based boards in order to post over 224fsb you typically need to set the pci-e frequency to a value of about 118mhz or so.
 
mrjminer said:
Just a question with your formula: does the HTT multi matter or simply the FSB (ie, actually processor mhz or just the fsb)?
Click to expand...
This is with Intel chipset, AMD chipsets will very and I would assume that the HTT will matter.
Just remember 100 is your base for your PCIe Freq you want to know what value to put here
Just remember 200 is your base for FSB you use your FSB to divide your power factor then add (+) it to your Base PCIe freq

Power factor/FSB you are trying to achieve= PCIe Freq
New value + Base PCIe Freq= OC PCIe Freq value.

Again this does not work with MB that are program to automatically adjust for the OC PCIe freq.
 
amd ati FO SHO said:
according to mods at dfi street ati = 105mhz, nvda 100 mhz
Click to expand...

The mods at dfi-street say 100MHz no matter what your card brand is. Some of them were saying 105MHz in the past but noone ever showed that it did anything at all. Some of the guys at xtremesystems though have been saying that a bump to like 110-120MHz is helping with their overclocks on X1900 XTX cards. I doubt only 105MHz would do much of anything. I'm testing out 110MHz to see if it helps stability any. I wouldn't push the PCI-E link very high though.
 
Eastcoasthandle said:
on newer Asus MB you leave it on auto as it will scale with your OC. However, other Boards require you to start at 100 and work you way up from there. I devised a formula that worked well with a restricted PG5D1 man it was a horrible board anyway. However I learned that the power factor for that MB is 2.2 which means for every 2.2MHz I increase the FSB I must increase the PCI-E Frequency by 1Mhz. This is a solid formula for that board. However, you must know the power factor for your board. However the P5WD2-2 Pre adjust automatically and if I go manually I will lock up.

This is a bit complicated because I have a P5GD1, 660, with a Corsair 3200C2PT (2-3-3-6 up to 225, 2.5-3-3-6 230 so far at 18x multi). I start off with a PCI express Frequency base of 100 with a FSB base of 200 then work my way up by a factor of 2.2 (for every 2.2 MHz on the FSB you increase your PCI express frequency by 1..

For example:
Your PCI Express Frequency has a base of 100. Your FSB has a base of 200.
If you increase your FSB to 230 then you increased your base by 30 MHz.
Divide that by 2.2 (30/2.2) and you get 13.63.
Round 13.63 up and you have value of 14 for your PCIe Freq.
I add 14 MHz to my PCI Express Frequency (100+14) and get 114 that I put in the bios
114 will be my new PCI express frequency at a FSB of 230.

Again this does not work if your MB is design to do this automatically. And, the 2.2 is for the P5GD1 only...as far as I know to date...
Click to expand...

By that logic i would need to be running mine at 154MHz and that seems really high for the PCI-E spec. I dont know anyone that overclocks their PCI-E clock very much at all on their overclocks with AMD. Have you ran any tests to see what exactly you gain by overclocking the PCI-E frequency in conjunction with the FSB? Are you able to achieve higher stable clocks?
 
burningrave101 said:
By that logic i would need to be running mine at 154MHz and that seems really high for the PCI-E spec. I dont know anyone that overclocks their PCI-E clock very much at all on their overclocks with AMD. Have you ran any tests to see what exactly you gain by overclocking the PCI-E frequency in conjunction with the FSB? Are you able to achieve higher stable clocks?
Click to expand...
Again, this formula was used on a P5DG1...And by my calculations (as you put it) I would be running a FSB of 320 if I wanted a PCIe freq at 154. Most extreme enthus. don't clock that high :p
 
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