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Overclocking PCIe Bus?

Last response: in Overclocking
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September 25, 2013 6:05:53 AM

I've looked it up, and could not find entirely conclusive results.

According to what I've looked up about it, It CAN yeild a healty boost in some cases, however not substantial. It can help with making your CPU overclock more stable, but more importantly, it can help stabilize more... extreme GPU overclocks. It also can potentially be dangerous.

So, I've got a GTX 650 with a rather large overclock of 215Mhz on the core and 425Mhz on the memory.

By default the PCIe Bus speed is set to 100. I'm thinking of going to 105 if it's not to risky, do you have any input?

(Oh, BTW, I FINALLY got a stable 3.25Ghz on my PII 720BE x3 with 4th core unlocked! Not super impressive to most of you I know, but it's a very nice boost. I just mixed it up, part HT ref clock, part multiplier, and of coarse I set NB to 2400 with some small voltage changes to most everything.)

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a b K Overclocking
September 25, 2013 6:15:34 AM

PCI/PCIe bus can be overclocked, but is very touchy, as it is what most secondary components talk across, you may get away with raising it a few mhz, but risk corrupting traffic.

I used to do it way back in the day, especially with AGP systems, but don't bother now and lock the bus to 100mhz.
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September 25, 2013 6:23:27 AM

would a 3-5 increase really cause anything but good, however small.
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a b K Overclocking
September 25, 2013 7:16:38 AM

from what i heard, even adding an additional 30MHz-40MHz, don't yield much performance gains.

i think the cons outweigh the pros.
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September 25, 2013 7:20:07 AM

Meh. My goal here is to get my hardware at it's best without spending anymore money. I'm probably no upgrading for 1 more year, so I'm trying to get this 2011 rig to work best it can.

I doubt there's much risk involved with such a small tweak.

i'll give it a shot, see what happens I guess.
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a b K Overclocking
September 25, 2013 7:24:43 AM

DukeOvilla said:
Meh. My goal here is to get my hardware at it's best without spending anymore money. I'm probably no upgrading for 1 more year, so I'm trying to get this 2011 rig to work best it can.

I doubt there's much risk involved with such a small tweak.

i'll give it a shot, see what happens I guess.


not much risk but, you'll probably see no gains either. let me know what happens :) 
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September 25, 2013 7:35:29 AM

Will do, I'm testing it today. As I've read, it can yield a decent boost on the low end FPS, esp if you're running a good overclock.
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a b K Overclocking
September 25, 2013 7:47:01 AM

DukeOvilla said:
Will do, I'm testing it today. As I've read, it can yield a decent boost on the low end FPS, esp if you're running a good overclock.


where'd you hear this? now im kinda interested but, unless your video card is specially designed to run with an overclocked PCI-E bus speed (i a limited amount of nvidia cards automatically overclock it) im pretty confident it won't do anything.

also, there are motherboards where a different component such as your SATA Controller run through the PCI-E as well; if you're HDD/SSD is using SATA, you can corrupt your data over time.

just be cautious; if it were me, id probably limit myself and test up to 125MHz but no higher. :) 
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September 25, 2013 7:51:46 AM

I've heard it a lot form many forums. I have a rather large overclock, so I think it could help. It has something to do with bandwidth....

I've also heard that cards that are PCIe 3.0 compatible, like mine, can benefit from a bit faster PCIe Bus.


As for the SATA controller going through the PCIe, I'll ask my manufacturer about that, but it should not be an issue.
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a b K Overclocking
September 25, 2013 8:11:04 AM

DukeOvilla said:
I've heard it a lot form many forums. I have a rather large overclock, so I think it could help. It has something to do with bandwidth....

I've also heard that cards that are PCIe 3.0 compatible, like mine, can benefit from a bit faster PCIe Bus.


As for the SATA controller going through the PCIe, I'll ask my manufacturer about that, but it should not be an issue.


the default bandwidth provided by a PCI-E 2.0 x16 lane will not hold your 650TI back. if you overclock the PCI-E bus, this presumably increases your bandwidth to a larger amount which would provide additional headroom. however, if the GPU is not fully saturating the lane already, there would be no difference.

PCI-E 2.0 x16 lanes provide a bandwidth of 8GB/sec while the recent PCI-E 3.0 offers double that @ 16GB/sec. the difference in these are negligible in almost all games.

even the GTX 590 and HD 6990 which both have dual GPUs couldn't saturate the bidrectional bandwidth provided by a single PCI-E 2.0 x16 lane. the 650TI can not fully saturate a PCI-E 2.0 x16 lane or even a PCI-E 1.0 x16 lane (although a PCI-E 1.0 x16's bandwidth would hold back higher end cards such as the GTX 670).
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September 25, 2013 8:22:35 AM

Don't care how it helps, only that it does by some magical manner.
:) 
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a b K Overclocking
September 25, 2013 8:39:35 AM

DukeOvilla said:
Don't care how it helps, only that it does by some magical manner.
:) 


haha, well it's your choice in the end but, if you saw claims of higher FPS somewhere on the internet, what i said proves that increasing bandwidth on a pci-e lane that's not fully saturated will have no effect. it's very straight forward that something that doesn't need "x" amount of bandwidth, will not need an even higher "x" amount of bandwidth. also, i dont believe overclocking PCI-E bus speed will do anything else besides increase bandwidth.

but, in theory, i guess it could help in minimum FPS because of the extra headroom during intense scenes in games that heavily stress the GPU.

good luck and will wait for your results. :) 
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a b K Overclocking
September 25, 2013 11:34:42 AM

I did play around with mine a while back. i heard anywhere from 100-110 is safe any more you will see wierd issues start occuring and no it will not kill your card


i may bump mine to 105 where it was a while ago to see if it helps my high OC
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September 25, 2013 6:51:57 PM

I put it to 110, no issues. like up to 3 more fps on the low end, so I'm happy.
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