Upping the PCI/AGP bus speed to gain video performance?!?!?

[Jumpem]

My dad says it gives him faster video benchmarks. Don't you want the AGP/PCI speeds to stay as close to 33/66 as possible? He just yelled at me and said I don't what I"m talking about, so can someone give me their opinions. Thanks!

It's on an Asus P4P800 with a P4 3.0.

 

[Duvie]

It is a delicate balance but I believe if the agp bus is faster then 66mhz then it actually increases the bandwidth of the card....If the card can take it and he may have to adjust vagp slightly to be 100% stable then there is nothing wrong with it. PCI bus pass 33mhz seems to be more fickle with many soundcards and nic cards not liking it.

The reason to lock the agp/pci at 66/33 is purely for safety to avoid those instabilities that can creep up. take the pci bus too far and you may corrupt the data on the harddrive and require a reformat or repair....

 

[zephyrprime]

I don't think it will really help with more than just synthetic benchmarks. Sure, you'll have more bandwidth. But is bandwidth the limiting problem? AGP 8x already has 2GB/sec of bandwidth. No system can write or encode anywhere near that much video per second.

 

[Jumpem]

Originally posted by: zephyrprime
I don't think it will really help with more than just synthetic benchmarks. Sure, you'll have more bandwidth. But is bandwidth the limiting problem? AGP 8x already has 2GB/sec of bandwidth. No system can write or encode anywhere near that much video per second.

That's what I told him, but he's never overclocked before. He says that I'm just trying to get him to do it "my" way. I'm so pissed.

 

[Soulkeeper]

I think there was a review somewhere where they increased the agp clock and it showed like 1% improvement at most
it's not really worth it, but yeah it can be done and does increase bandwidth
just be carefull with yur agp voltage and make sure you don't up the pci bus too high or your hard drives might corrupt, sound could stop working, lan could stop working, or the system could just become unstable


good luck

 

[Jeff7181]

The only way I can see it helping is if you have a motherboard that only supports 1 or 2 X AGP... in that case, increasing the speed would increase the bandwidth, which would be necessary for say a Ti4600 or higher. However... the performance gains are very small if you're running at least 4X AGP. I tested it a while back with my Ti4200... and increasing the AGP bus from 66 to 85 with 4X AGP didn't produce ANY noticeable gains. But when I set the card to 2X AGP, there was about an average of a 3-5% performance increase. So... with 8X AGP, I wouldn't expect any gains by overclocking the AGP bus... mostly all it does is reduce stability.
The increases in speed I would probably attribute to the reduced latency of the higher clock speed, rather than the increased bandwidth.

As far as the PCI bus... hard drives are VERY sensative to the PCI clock frequency. Normally it's 33 Mhz... when it gets up around 38 or 40, you can expect to see some random data corruption, BSOD's, and lockups... up around 45, you'll be lucky to boot into Windows, and other devices like sound cards and NIC's and modems will start to have problems. Yes, there are some people who don't have a PCI lock on their motherboard, and are able to run the PCI bus around 40-45 Mhz with stability issues, but that's a rare occasion. There are exceptions to every rule, but I wouldn't count on being that 1% of people who don't have stability issues above 40 mhz =)

 

[Jumpem]

Thanks for the help guys.

 

[pillage2001]

Your dad overclocks and yell at you for not believing him??? You rule, dude.

 

[DerwenArtos12]

Yeah it can help but only in synthetic benchies and to so small a degree that it is almost unmeasurable. In actual gaming perfomance i would be amaized if it gave him 2fps average. As someone already did say it does help significantly more when you are running a card capable of 8x on a mobo that is only capable of 4x.