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Help. PCIeX16 scaling down when I OC...

Last response: in Overclocking
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June 19, 2007 12:35:13 AM

This just started happening a day or two ago, well in it's current form at least.

Occasionally, when my PC might crash while playing a game, it would boot back-up and performance would be slow. I somehow discovered that my PCIx16 port was being scaled down to x1, resulting in poor performance. I figured out that by loading optimized defaults in the BIOS and then redoing my overclock, I could fix it. Well, apparently no longer. Now, I can load my stock settings and all works fine. PCIx16. But, as soon as I overclock the CPU, it immediately drops the PCIEx16 down to PCIEx1. Any idea's what's going on? Am I not getting enough power from the PSU and so it's scaling it down? What's going on?

Gigabyte DS3 (Rev 3.3)
E4300 (When OCed: FSB 300, V.Core 1.4)
2 Gigs G.Skill DDR2 800
GeForce 8800GTS 640meg
Windows XP
Fortron 400W (Max 450W) PSU

So far, I've determined that it's unrelated to how much voltage I give. I set the FSB to 250 without any voltage modifications and it still scaled it down to 1x. As well, I've changed nothing with the PCIe slots in terms of speed. They've always been set to auto and always worked fine. I also manually set the speed at 100 and it still scaled it down.

This is getting really frustrating. I'm ready to give up on OCing and just buy myself a better, higher clocked processor.

Thanks.

More about : pciex16 scaling

June 19, 2007 2:24:38 AM

Unfortunately, it doesn't. I read through it a few times and looked to see if there was any good information about doing something to the PCIx16 slot and there wasn't.

Maybe they have forums or have dealt with this issue before...

Thanks though.
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June 19, 2007 3:06:36 AM

In the Step1 screenshot, you will see these. Robust Graphic Booster (thats set you Auto) and in Step4 you should see, PCI Express Frequency(Mhz) also set to Auto.

Is there any way you can check to see if you can change those setting to fix your problem.

Otherwise you most likely will need to email Gigabyte Support with your problem.
June 19, 2007 3:50:08 AM

I would have to say that when your overclocking your system it drawing to much power and your video card is scaling down to prevent damage.

I could be wrong but I dont think so, Can you get your hands on a stronger PSU and test it out that way ?
June 19, 2007 4:09:11 AM

Quote:
In the Step1 screenshot, you will see these. Robust Graphic Booster (thats set you Auto) and in Step4 you should see, PCI Express Frequency(Mhz) also set to Auto.

Is there any way you can check to see if you can change those setting to fix your problem.

Otherwise you most likely will need to email Gigabyte Support with your problem.


They're both off. I messed around with both of them and toyed with different settings to no avail.

Quote:
I would have to say that when your overclocking your system it drawing to much power and your video card is scaling down to prevent damage.

I could be wrong but I dont think so, Can you get your hands on a stronger PSU and test it out that way ?


This is still my original theory and guess. However, it doesn't seem to make sense that it would work properly for a while and at greater voltages (had a higher OC and using 1.45vcore as opposed to 1.4 and 1.375 as I was using later) and then all of a sudden cease working properly.

It's also weird that it does it just by increasing the FSB to 250 without touching any voltages.

But, I'm going to see what happens when I get my RMA'd PSU from Antec which should be 550W or so. We'll see.

I'm also going to email Gigabyte as suggested and see if they can provide an answer.
June 19, 2007 3:22:21 PM

I have the same motherboard and CPU and have an 8800GTX. I haven't experienced this myself, but have read about others that have. Sometimes they say to manually set your PCI Express to 100, sometimes they say it should be a little higher, I've seen suggestions go as high as 110. It seems to go up more as people overclock more. So you might play with that if you haven't already.


However I'm kinda thinking it's your PSU also. While you may not be increasing voltages, just by increasing overclocks on the CPU and FSB, you are increasing wattage usage, even if you aren't adding more volts.

Example, using a PSU calculator I can see overclocking a E4300 from 1.8GHz to 2.7GHz (your 300FSB if you left the multiplier at 9) results in the CPU going from 65 watts, to 98 watts, even with the voltage left the same.

Your graphics card's wattage use also scales up from idle to load. Your motherboard is using more watts with a higher FSB I'm pretty sure as well.

The PSU sounds like it's being over worked when you start stressing the CPU and GPU at the same time.
June 19, 2007 4:04:11 PM

Setting (G)MCH +0.1V fixed it for me.
June 20, 2007 12:25:18 AM

Quote:

However I'm kinda thinking it's your PSU also. While you may not be increasing voltages, just by increasing overclocks on the CPU and FSB, you are increasing wattage usage, even if you aren't adding more volts.

Example, using a PSU calculator I can see overclocking a E4300 from 1.8GHz to 2.7GHz (your 300FSB if you left the multiplier at 9) results in the CPU going from 65 watts, to 98 watts, even with the voltage left the same.

Your graphics card's wattage use also scales up from idle to load. Your motherboard is using more watts with a higher FSB I'm pretty sure as well.

The PSU sounds like it's being over worked when you start stressing the CPU and GPU at the same time.


Thanks for that info. I'm definitely still going to try and resolve this once I get my new PSU. Hopefully sometime this week...

Quote:
Setting (G)MCH +0.1V fixed it for me.


This seems to have solved my problem for the time being. I initially tried overvolting the PCIe or whichever it is that pertains to...I think the north bridge...and it did nothing. However, this has solved my problem for now. I'm hoping once I get the new PSU though, I can not have to worry about overvolting this bridge much...
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