PCIe What's the Deal?

[garyinhere]

I'm am long time reader and a first time "poster". I have been climbing the latter on how to properly overclock my computer. Always treading the fine line of stability to performance. On my new build I bought top of the line or close to top of the line everything. Completly new at overclocking I didn't realize the amount of factors their were to tweak and change to obtain a performance boost. But, the one thing I did know is that you don't mess with the PCI setting, or at least never take it past 110. My BIOS lets take it to 160 if I wanted. Uasually my BIOS will turn things red or yellow or purple when I reach a danger zone but it doesn't seem to be worried about my PCIe setting. I have never been able to find anything stating the purpose of leaving that setting alone. So I downloaded AMD's overdrive utility and realized that it was tweaking that setting. So I set it in BIOS and that setting made my system stable? So my question is what is the primary purpose of the PCI setting and does it have a High that will damage any components?

 

[erocker]

So I set it in BIOS and that setting made my system stable? So my question is what is the primary purpose of the PCI setting and does it have a High that will damage any components?

Now look what you've done "first time poster." Everyone is going to be clamoring to their rigs and adjusting PCI-E settings. This is pretty interesting, what do you have it set to? You didn't specify. I would like to know why your system is stable with higher PCI-E frequency, I have no idea how that would work!

 

[DRDNA]

I have always run mine at 104 to 110ish....opens the band width some for my crossfire set ups I have run...my 24/7 is at 104...and yes in GPU test suites i see a bit of a difference to the positive side of things....now I don't know about non crossfire any more cuz I have been running CF for about 5 years now...I doubt that a single card would see much or for that matter duel set up but crossfireX should benefit.

 

[garyinhere]

Now look what you've done "first time poster." Everyone is going to be clamoring to their rigs and adjusting PCI-E settings. This is pretty interesting, what do you have it set to? You didn't specify. I would like to know why your system is stable with higher PCI-E frequency, I have no idea how that would work!

I set mine to 108... the system is stable. It wasn't before wouldn't even run a benchmark. My settings are at: 20x 200bus 108PCI CPU/NB2000 HT/LINK2000 CPU/VLTS 1.6 DRAM1.7
Now before you go tweaking away I am still having a hard time passing a stability test. I have played Just Cause for about an hour and a half with no crashes... I never turn my system off but it jst doesn't seem to run prime or anything else but I have never crashed besides the stability tests. It will do anything I ask it too but a stability test? temps are in range too... CPU around 57 underload on air cooling

 

[theonedub]

The PCIe setting is a mystery to me too. EVGA_Jacob over @ the EVGA forums advised that upping the PCIe clock on the P55 board would increase/maximize the Base Clock frequency. In his P55 OC guide for 4.2ghz stability on an i7 he recommended 104mhz. So there is some credence to what you found, just not much explanation.

 

[TheShad0W]

I set mine to 108... the system is stable. It wasn't before wouldn't even run a benchmark. My settings are at: 20x 200bus 108PCI CPU/NB2000 HT/LINK2000 CPU/VLTS 1.6 DRAM1.7

1.6 is a bit much, if you need that for 4Ghz then frankly your chip isn't up to 4Ghz.
What are you using to test these settings and what sorta temps are you getting?

 

[garyinhere]

1.6 is a bit much, if you need that for 4Ghz then frankly your chip isn't up to 4Ghz.
What are you using to test these settings and what sorta temps are you getting?

I know it's on the verge of high but my load temps are well in range. I use Prime and also AMD's overdrive and several others plus benchmarks to monitor my temps. Under load I get to around 59 never hit over 61

 

[TheShad0W]

I know it's on the verge of high but my load temps are well in range. I use Prime and also AMD's overdrive and several others plus benchmarks to monitor my temps. Under load I get to around 59 never hit over 61

It's not "on the verge of high" - it's a voltage that will probably cause degredation of the chip - shouldn't take too long either.
cadaveca even demonstrated this
http://forums.techpowerup.com/showthread.php?t=114552

1.5 is considered relatively safe, wouldn't go much over that personally unless I wanted to be upgrading my CPU every 6-8 months

 

[garyinhere]

It's not "on the verge of high" - it's a voltage that will probably cause degredation of the chip - shouldn't take too long either.
cadaveca even demonstrated this
http://forums.techpowerup.com/showthread.php?t=114552

1.5 is considered relatively safe, wouldn't go much over that personally unless I wanted to be upgrading my CPU every 6-8 months

I read most of the thread and it seemed that He was concerned about going over 1.6 if his temps were over 50... if i read the thread correctly i am well in range.

 

[DirectorC]

You have your CPU set to 1.6 volts?

And no one has said this is probably what's making your system crash?

 

[garyinhere]

You have your CPU set to 1.6 volts?

And no one has said this is probably what's making your system crash?

My system isn't crashing. It will do anything except run prime for a period of time... games photoshop whatever it does it all... also i am still tweaking... my main question was dealing with lack of PCI knowledge by the masses on Bios. Their jst doesn't seem to be anyone that knows limits and such.

 

[bonzai_cyberninja]

what settings are you running interms of fsb, multi, and nb etc?

 

[jellyrole]

Hmm, you've got me thinking now...gonna have to see if upping that PCI setting in bios will allow me to take my 5870 to 1100MHz.

 

[Mussels]

raising the PCI and PCI-E clocks does nothing for performance.

In some very rare circumstances it can help you get a slightly better system OC, but 99% of the time it gives you no benefit, and causes problems (SATA controllers corrupting data or not showing drives, things like that)

 

[garyinhere]

raising the PCI and PCI-E clocks does nothing for performance.

In some very rare circumstances it can help you get a slightly better system OC, but 99% of the time it gives you no benefit, and causes problems (SATA controllers corrupting data or not showing drives, things like that)

That's the main reason for the thread to figure out this robin hood setting... why would bios not tell you it'll harm anything? Why give you the option of 100-150? This setting is for something and no one seems to know for what??? I did stabilize my OC and I jst want to know why???

 

[Mussels]

That's the main reason for the thread to figure out this robin hood setting... why would bios not tell you it'll harm anything? Why give you the option of 100-150? This setting is for something and no one seems to know for what??? I did stabilize my OC and I jst want to know why???

because when you raise your FSB, a divider is used to keep the PCI-E setting at its default of 100Mhz (and thus, PCI at 33Mhz).

Sometimes those dividers arent as stable as others, therefore, changing the frequency can make a different divider be used, making the OC more stable. The opposite is also true, you could change it to a divider that is less stable, or causes problems.


You'll also notice your BIOS doesnt mention that running CL5 DDR2 ram at CL2 could be a dumb idea - BIOS doesnt hold your hand, it assumes you know what the setting does before you change it.

 

[garyinhere]

because when you raise your FSB, a divider is used to keep the PCI-E setting at its default of 100Mhz (and thus, PCI at 33Mhz).

Sometimes those dividers arent as stable as others, therefore, changing the frequency can make a different divider be used, making the OC more stable. The opposite is also true, you could change it to a divider that is less stable, or causes problems.


You'll also notice your BIOS doesnt mention that running CL5 DDR2 ram at CL2 could be a dumb idea - BIOS doesnt hold your hand, it assumes you know what the setting does before you change it.

ouch! just looking for an answer seems like this puzzles alot of people not jst me... so it's for OUR benifit... do you have documentation on anything cause i'd love to read it!

 

[Mussels]

nah, no documentation. it all just floats around in my head.

 

[garyinhere]

nah, no documentation. it all just floats around in my head.

NICE!!!

 

[jasper1605]

nah, no documentation. it all just floats around in my head.

where did it all come from, I would wonder?

 

[DirectorC]

where did it all come from, I would wonder?

Documentation. Shhh!

 

[Mussels]

where did it all come from, I would wonder?

from a mispent youth staring at a windows 95/98 defrag screen, until all the pretty colored blocks finally made sense. I dont even see the code anymore, its just blonde, redhead, brunette...

 

[garyinhere]

If you could get your rig to 4.2 safely wouldn't you want to know how it's done... I research everything and jst wanna know what is going on with PCI... we are getting off topic here!

 

[Mussels]

If you could get your rig to 4.2 safely wouldn't you want to know how it's done... I research everything and jst wanna know what is going on with PCI... we are getting off topic here!

i can get mine to 4.4 i just didnt like the temps, or need the extra power.


And matrix jokes are NEVER off topic!

 

[garyinhere]

i can get mine to 4.4 i just didnt like the temps, or need the extra power.


And matrix jokes are NEVER off topic!

I know all bout the matrix NEO...:::;> jst meant that we need to get back at what makes things stable and why... ie the PCI