The Big PCI-E Mystery.

Hi,

I've spent a lot of hours on the net recently looking for a proper explanation of consequences of changing the PCIE bus frequency. Some ppl say it's dangerous and it can cause permanent damage of the GPU, others say that PCIE freq is just a data rate and as such can't cause any damage whatsoever. Some advise to leave it set to AUTO, others say to not to go over 120...

Needless to say I'm confused.

I've been messing around with my E7200@GA P31-DS3L for a few days now. It's set to 3.16Ghz (333x9.5) now. If I want to set FSB to 400 I have to either leave PCIE at AUTO or set it manually to 118 ( that's the lowest setting I found by hit&miss ). My PC won't POST otherwise.

I'm a noob when it comes to overclocking, a very confused noob.

One more thing: Is there any program that can read PCIE freq? I'd like to know what's happening when it's set to AUTO. EasyTunePro doesn't show anything.

Are you OCing with EasyTunePro?

Or are you entering the settings manually in the Bios?

You should definitely be able to lock your PCIe at 100 mhz no matter what you have the FSB set at. If you can't something is drastically wrong in your Bios or EasyTune is presuming it isn't locked and giving you false readings.

I've seen parts fried from extended periods at even 110 mhz. It's really not worth the chance for the extra bandwidth that is completely unused anyways.

OK, let me see if I have this correct:

You entered in the Bios under PCIE frequency: 100 mhz

Then if you change the FSB (cpu host frequency) value to 380 it automatically changes the PCIE frequency (to 112) in the Bios without you touching it and won't let you enter 100.

Is this what is happening?

Strangest thing I've never come across. Bios pics with available PCIE options for the higher FSB settings would be of great interest if you would, and I'll see if anyone else has had this problem.

OK, I did some pictures:

FSB set to 400 with PCIE at 100:

Knowing it's not going to work, I hit F10 and after few moments my PC boots with following settings:

As you can see, all the settings are reverted to default, except multiplier which strangely stays at 9 (it's 9.5x266 by default).

The whole point behind my questions is that one could set his/hers PCIE to AUTO and not realize that it's not gonna be 100MHz, risking damaging GPU or SATA drives... There's a P35 overclocking guide on this forum, just a few posts below mine and the guy says to set PCIE to 100 or leave it at AUTO... well it looks like it's not such a good idea, not in my case at least...

First of all, many thanks for your replies, RJR.

I've found the answer to my problem, I think:

Aussie overclocking forum

It looks like it's a common problem with Gigabyte's P31 motherboards. In other words I'll be doing some shopping soon

Thanks again for your help and best of luck to you, dude.

I'm going for GA-EP45-UD3L, decided to stay with Gigabyte as their BIOS is easy to understand for a noob like me.
You should start a new thread, antemon - I'm a noob and there are a lot of ppl here who are way more experienced than me and will be more than happy to recommend a good mobo to you.



For all those unfortunate poor souls who own a P31-DS3L:

I've found another info regarding the PCIE setting. If you want to set the FSB higher than 333Mhz use the equation below to calculate your PCIE freq:

FSB / 3.33 = PCIE

I finally got it clarified by one of the moderators on Gigabyte support forum.

His response:

Budget boards such as P31 or P43 will need PCIE set to above 100 for overclocking generally. Auto is not advised because when you raise the FSB the PCIE Freq will also increase automatically.

I suggest 100-110 as a safe range, but anything above 100 can damage your board/GFX Cards, and Hard drives. So it is all up to you, but manually set it for sure.

If you want to run 400 FSB, and have to use 118 I do not suggest that or you will damage something for sure. I suggest a new board, P35 if you do not have much money, or P45-UD3x models are all around $90-120

link to my thread


I had read this review before I bought this board, they pushed it to 465mhz, that would give a "healthy" PCIE frequency of 140mhz. I can almost smell their GPU frying...