How do I stabilize a PCIE frequency overclock on an Asus Rampage III extreme mobo?

[l88bastard]

I am running an Asus extreme III rampage mobo with a 980x overclocked to 4.7ghz on water with a Corsair H100 and a Asus CUII 6970 trifired with a XFX 6990. My overclock is stable if I back the PCIE frequency down to 100, but having the frequency set to 110 makes a HUGE difference when I play BF3 @ 5852x1080 res. The overclock smooths out allot of the random jitteryness & adds 5-10 fps to my minimum fps, so I am able to cap my FPS at 70hz instead of 66hz (I running 120hz S27A750 monitors).

Sometimes my computer will go for three hours without a BSOD and sometimes it will BSOD a few times back to back. I've tried backing down my processor overclock, but it it definantly the PCIE frequency OC thats causing the pain. Is there any voltages I can up which will make my PCIE frequency overclock stable? I see IOH PCIE voltage & ICH PCIE voltage, which are both currently set to "auto." Would messing around with these help or hurt? I'm a little lost when it comes to PCIE voltage overclocking and I don't wanna fry my precious.

 

[bigddybn]

What you are describing just plain doesn't make sense.

Have you tried simply overclocking your GPUs with a 100mhz PCI freq? Overclocking the bus speed is essentially widening a 10 lane highway that you were only using 2 lanes of to begin with.

 

[Forceman]

Overclocking the PCIe bus (especially that far) is really not a very good idea. Your crashes are probably coming because the video card can't run effectively at such a high bus speed.

 

[Brampton_Boy]

I actually managed to ruin my old 4890 running the PCI-E Bus significantly out of spec (112mhz).

I have heard of people increasing it to 102-103mhz to help stabilize overclocks on the LG1366 i7s, but not for the purposes of boosting frame rate.

 

[l88bastard]

What you are describing just plain doesn't make sense.

Have you tried simply overclocking your GPUs with a 100mhz PCI freq? Overclocking the bus speed is essentially widening a 10 lane highway that you were only using 2 lanes of to begin with.

PCIE Frequency - The default is 100MHz,raising this improves texture loading times across the board (due to faster data speeds and increased available bandwidth over the PCIE bus) "safe" settings for this are between 105 - 110MHz.

The whole idea of increasing the PCIE bandwidth isnt because the video cards transfer 4GB of data each second EVERY second (standard speed), but because when the cards need a burst of data (stuff in the ram that didn't fit into texture memory), it will occur faster, creating less of a bottleneck to all the other data transfers that it has to do.

Overclocking the PCIe bus (especially that far) is really not a very good idea. Your crashes are probably coming because the video card can't run effectively at such a high bus speed.

Tweeking up the PCIe to between 107-112 can improve stability in an OCed system. Beyond 112, according some can damage the Vid Card.

 

[Forceman]

PCIE Frequency - The default is 100MHz,raising this improves texture loading times across the board (due to faster data speeds and increased available bandwidth over the PCIE bus) "safe" settings for this are between 105 - 110MHz.

The whole idea of increasing the PCIE bandwidth isnt because the video cards transfer 4GB of data each second EVERY second (standard speed), but because when the cards need a burst of data (stuff in the ram that didn't fit into texture memory), it will occur faster, creating less of a bottleneck to all the other data transfers that it has to do.

I'd like to see some testing to back up that claim. Chopping the PCIe bandwidth in half, by running at x8, doesn't cause any significant decrease in performance, so I find it hard to believe that adding a 10% bus speed increase is going to make much difference.

 

[l88bastard]

I'd like to see some testing to back up that claim. Chopping the PCIe bandwidth in half, by running at x8, doesn't cause any significant decrease in performance, so I find it hard to believe that adding a 10% buss speed increase is going to make much difference.

This dude got a 1-5% increase in tests...
http://www.tomshardware.com/forum/260686-29-pcie-frequency-helping

but its not about the increase, its actually making my trifire feel smoother...it almost feels as smooth as one card now......almost

 

[Forceman]

This dude got a 1-5% increase in tests...
http://www.tomshardware.com/forum/260686-29-pcie-frequency-helping

but its not about the increase, its actually making my trifire feel smoother...it almost feels as smooth as one card now......almost

So a 30% bus overclock netted 1-5% performance increase? Not too impressive. Plus, that was on a P55 motherboard, which has half-speed PCIe 2.0 links.

I'm glad you feel like it helps your system, but I'm sure you can see how "feels smoother" doesn't really help justify it. If it helps stability, that's one thing, but doesn't seem worth the risk/hassle for the small measurable performance increase.

 

[error-id10t]

Using 3DMark11 as an example and comparing 2 different OC you'll see a difference.

Say 46x100 compared to 44x104.5 .. the last one will give you a higher score in basically any bench. The problem is that Prime will more than likely fail, it absolutely hates BCLK OC and I've yet to see anyone get more stability with raising it.

 

[l88bastard]

So a 30% bus overclock netted 1-5% performance increase? Not too impressive. Plus, that was on a P55 motherboard, which has half-speed PCIe 2.0 links.

I'm glad you feel like it helps your system, but I'm sure you can see how "feels smoother" doesn't really help justify it. If it helps stability, that's one thing, but doesn't seem worth the risk/hassle for the small measurable performance increase.

Alright buddy thanks for your fascinating hep, now please move it along and troll someone elses thread. Dont bother replying im putting you on ignore.

 

[Forceman]

Using 3DMark11 as an example and comparing 2 different OC you'll see a difference.

Say 46x100 compared to 44x104.5 .. the last one will give you a higher score in basically any bench. The problem is that Prime will more than likely fail, it absolutely hates BCLK OC and I've yet to see anyone get more stability with raising it.

If you are talking about BCLK overclocking, then that also overclocks the memory link, which can, depending on the situation, help a lot.

Alright buddy thanks for your fascinating hep, now please move it along and troll someone elses thread. Dont bother replying im putting you on ignore.

Glad to help - anytime you want to overclock 30% for a 5% gain, feel free to hit me back up.

Anyway, OP, if you do want to run the PCIe oveclock, the GPU PCIe lanes are running off the IOH, so I'd try bumping that up a notch or two and see if it helps. Not sure what the default it, but there are some tests where it was being run at 1.36V, so that gives you a window to try, at least.

 

[__hollywood|meow]

first of all, sometimes hard disk controllers are tied to the pcie clock so you need to watch the hell out touching it. secondly, if it isnt, dont run it more than literally a couple mhz over spec to stabilize an OC for an extended period of time. the only time ramping the clock up (~111mhz) is a "good idea" is to get more pts in benchmarks (yes, forceman, it helps bench scores. just because youve never benched things doesnt mean the established methodology is ineffective)

tldr you might kill your cards bro. be careful.

 

[Forceman]

For the record, I never said it didn't help benchmarks. I said that the small increase it makes isn't worth the long-term risk of running it out of spec as a day to day tactic. If it helps you stabilize a BCLK overclock, that's fine and dandy, but be aware that it can cause other problems - sort of like what the OP is having. Not all video cards can handle running out of spec - and, as you pointed out, other clock speeds can also be tied to the PCIe speed (not sure if that is still the case today, but certainly was true a few years ago).

 

[l88bastard]

first of all, sometimes hard disk controllers are tied to the pcie clock so you need to watch the hell out touching it. secondly, if it isnt, dont run it more than literally a couple mhz over spec to stabilize an OC for an extended period of time. the only time ramping the clock up (~111mhz) is a "good idea" is to get more pts in benchmarks (yes, forceman, it helps bench scores. just because youve never benched things doesnt mean the established methodology is ineffective)

tldr you might kill your cards bro. be careful.

Eh, looks like the instability was still from my CPU overclock and not the PCIE Frequency after all. I just bumped up the CPU voltage a little bit more and it seems to have taken care of the issue.

With regard to the PCI Frequency OC to 110. That looks pretty safe, most people say going higher than 120 is when you start to hit danger...to the guy earlier that said 112 fried his video card, well your card could have died for many other reasons besides the PCIE OC, it could just be coincidental.

Im running a Rampage III and a CUII 6970, im pretty sure they can take the 110....they were built for much worse abuse.

 

[Falkentyne]

I actually managed to ruin my old 4890 running the PCI-E Bus significantly out of spec (112mhz).

I have heard of people increasing it to 102-103mhz to help stabilize overclocks on the LG1366 i7s, but not for the purposes of boosting frame rate.

How did you ruin a 4890? I had a 4870 and a 4890 and I ran 24/7 PCIE overclocks of *115 mhz* on a socket 775 board, for years, and nothing happened to the cards. I don't think I gained very much from it, though.