benchmarking PCI-E bus frequency

[monohouse]

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[Deleted member 3]

Increasing the bus can increase performance a bit, NV does it on some models by default.

Both NB and SB can handle PCI-e, PEG slots are connected to the NB though.

You don't cool a bus.

Stability problems can be serious, once your storage controller shits out you can end up with corrupt data.

 

[alexp999]

damn ! the storage is a major problem, is there a way to avoid it ?
I have north bridge water cooling, so if that is what is used in my case I am lucky, but if it's the south I may not have much to do with that, except of corse the silver paste I used to replace the silicon crap that was there when I first bought the mobo, do you know how much is "a bit" ? you have some experience ?

Why do you want to increase the PCI-E bus speed anyway??

Most people on here say to lock it at 100Mhz and never increase it. It can do all sorts of damage for a negigable increase (if any).

 

[Deleted member 3]

damn ! the storage is a major problem, is there a way to avoid it ?
I have north bridge water cooling, so if that is what is used in my case I am lucky, but if it's the south I may not have much to do with that, except of corse the silver paste I used to replace the silicon crap that was there when I first bought the mobo, do you know how much is "a bit" ? you have some experience ?

Have a storage controller that doesn't mind high PCI-e bus speeds. Not sure which do or don't.

Depending on your harddrives a PCI controller might be a workaround. Assuming the PCI bus isn't overclocked as well.

 

[Deleted member 3]

Why do you want to increase the PCI-E bus speed anyway?

The first question would answer that by itself, increased performance. And sure it could damage things, overclocking anything could do that. Most people here do it because they can, stopping at the PCI-e bus is for girls

 

[Sasqui]

Yea, stability is the issue. Somewhere around 110-115 certain components can't handle it.

No performance increase that I know of, though I have yet to see anyone benchmark the PCI-E specifically (all other things constant). Any takers?

 

[RatusNatus]

before I start I would like to ask if anyone knows:

1. whether increasing PCI-E frequency increases video performance
2. which component is handling the PCI-E (south/north) and whether increasing the frequency of that component will increase the overclockability of the PCI-E bus
6. what is the maximum known stable PCI-E frequency when overclocked from the default 100 Mhz, and what is the known common overclockability

1- dont know.
2-Sata things... with 120-122, my old mobo wont see it.
6-110-115 i do use 105.

 

[Kei]

Yea, stability is the issue. Somewhere around 110-115 certain components can't handle it.

No performance increase that I know of, though I have yet to see anyone benchmark the PCI-E specifically (all other things constant). Any takers?

I've been down that road and there is indeed extra performance to be had by tuning the PCI Bus speed clock. Of course this is not something that anyone skittish or with little experience should jump into due to the problems it could cause.

AMD 790FX boards come with a feature (at least the ASUS M3A32) called AutoXpress. This is a stock feature that overclocks the PCI Bus clock all the way up to 124Mhz if you have it enabled. The thing with the PCI Bus is that you have to experiment and find what clock your particular card likes to run at. Not all cards are the same even if they're from the same brand so some cards may react better or not at all.

On average using two ATi 3870's in crossfire I was able to gain at the least 400 marks in 3dmark06 with some settings gaining even more. I've attatched two screen shots of 3dmark06 results from PCI Bus clock tuning only. The tests were done on my Phenom 9850BE when running on only two cores with dual 3870 cards clocked at 880/1200 (max was 905/1305 when run together).

Hope this helps but remember your results may (and probably will) vary and your card may get nothing at all or more. Do this at your own risk as just like any other overclocking you can indeed kill your system so you determine if it's worth it to you...

K

Also note that the higher the Bus speed does not mean a higher score/performance it's a very specific range where performance will be gained if at all. I do not recommend going over 110Mhz if you do not see any gain by that time unless you're using an AMD 790FX chipset which has the factory stock option to go up to 124Mhz automatically.

 

[Kei]

On another note the final score for the system was 16,058 marks though I did not do PCI Bus clock tuning on the max clocks which would've put the final score at approximately 16,450 marks. On each setting I tested (lots) each and every one gained at the least 400 marks so I have no doubts whatsoever that it would have achieved 16,450 no problems.

I have not done PCI Bus tuning nor overclocked the 4850 which I am currently using (the rest of the system has not changed).

K

 

[Sasqui]

^ Kei - Learn something new every day - thanks.

 

[Kei]

^ Kei - Learn something new every day - thanks.

My honor to help

K

 

[Ketxxx]

Increasing the PCIE bus can have a noticable boost in some circumstances. It largely depends on how powerful your graphics card is. If OCing the PCIE bus I don't recommend a frequency above 120MHz as onboard SATA controllers can throw an absolute fritz and corrupt data on the HDD. "Safe" settings for the PCIE bus are anywhere between 101-110MHz, beyond that your starting to live a little dangerously.

 

[oli_ramsay]

Well I've got mine at 115 and have had for some while, but I think after reading all the above posts I'll turn it down to 110 just to be on the safe side.

 

[Kei]

No, I ran testing on both the single card and dual card solutions with my 3870's. There were gains on both setups though not as much with a single card.

K

 

[CrackerJack]

I had my 790X all the way up to 120mhz. Never ran into a problem, and got a pretty good increase. But I haven't done really increase with the790FX. But I have notice if I don't manuall change the bus to 100mhz. It will be all the way up to 130mhz But the cpu tweak option was on. But Kei, would that cause the bus to increase that high if the tweak options is enabled? Is it better off or on?

initial results at 110 mhz seem to increase something, but it's nothing that can be noticed ingame, not even 0.1 fps

Try using 3dMark06 or even FurMark

 

[Tatty_Two]

Run mine at 110mhz, the difference on my current GTS between 100 and 110mhz was exactly 180 3D Mark 2006 points. personally I would not go above 110mhz for prolonged use and SLi/XFire in particular benefit from the increased bandwidth.

 

[CrackerJack]

I just test mine again. Cpu Tweak enabled in bios and Bus Speed set to auto. And overdrive shows 124mhz. Is that too high, for a 790FX board. I wouldn't think so, since that's the factory settings.

@ monohouse most of us run at 1280x1024. But in this case, it doesn't matter. Thought I would warn you if you went to share your score at the FurMark thread.

 

[CrackerJack]

110mhz is usually the sweet spot. And the safer.

 

[mitsirfishi]

stock is not an option

 

[JrRacinFan]

Take this as a grain of salt, I have mine locked at 105mhz. Anyone know if it would cause problems with anything >120mhz if I use IDE hdd's with a SATA burner?

 

[sneekypeet]

Take this as a grain of salt, I have mine locked at 105mhz. Anyone know if it would cause problems with anything >120mhz if I use IDE hdd's with a SATA burner?

I didnt have issues up to 115 hith an IDE HDD. I started loosing things like the ethernet and USB ports before I had any OS corruption. Concider those as signs you are pushing too far!

 

[The Haunted]

I ran 3dmark06 on a 4870 at different bus speed and here the results:


As you can see, there is no real improvement in raising the pcie bus speed.
But if i remember well, on my nforce4 + 1900xt a 110mhz bus gave me 25 more mhz overclock on that video card.

 

[Kei]

I had my 790X all the way up to 120mhz. Never ran into a problem, and got a pretty good increase. But I haven't done really increase with the790FX. But I have notice if I don't manuall change the bus to 100mhz. It will be all the way up to 130mhz But the cpu tweak option was on. But Kei, would that cause the bus to increase that high if the tweak options is enabled? Is it better off or on?

Hey Cracker, the reason your bus speed is clocked at 124Mhz is not because of the CPU Tweak option (that is for AOD 'red' mode only). Your bus speed is higher than the 100Mhz you set it at because the "AutoXpress" option is turned to either Enabled or Auto which will raise the bus speed to that speed.

It's a feature that comes stock on our 790FX boards from AMD so there is no worry in it. Though this is a stock option it may not be the best option for performance of your card and you'd have to do testing at different speeds to find the best for your system and specific card.

K

Btw, I leave AutoXpress and CPU Tweak both disabled for temperature reasons and because I don't need my bus speed that high. CPU Tweak adds roughly 5-10C to a Phenom w/little to no gain in overall performance so it should be used only for benchmarking.