Overclocking CPU without changing FSB?

[Davste]

I have an old Athlon 64 x2 4800+
It's meant to run at 2.5Ghz, but I can get it up to 3Ghz.

I overclock by changing my FSB speed, and had to up my ram voltage to 1.9v to get it stable at 2.9Ghz. So now I try to be happy with 2.85Ghz with the upped voltage until I get a new CPU. It doesn't matter really if this CPU fries or explodes in a spectacular way

Unless I'm not mistaken, changing the FSB speed overclocks everything, not just the CPU. The thing is, I am getting some artefacts in games when I overclock it. I have a radeon HD 6850. This card is meant to have a huge overclocking headroom - but I have a version which was pre-overclocked. Powercolour 6850 PCS+, originally at 820Mhz. I can't change the voltage on this card because it's powercolour, and I don't want to either, because I don't want to void the warranty.

For example, skyrim runs really fast at 1920x1080@High, but I sometimes get random texture flickering. One time the ingame menu (ESC) was with a completely green background. I don't like it and I hope I'm not damaging this card. Is it possible to overclock my CPU (and maybe RAM) without overclocking my graphics card?

 

[Cerb]

You could very well be seeing artifacts from overclocking your CPU (memory controller) too far, rather than your video card, too.

I don't recall if raising the hypertransport speed OCed everything for most AM2 chipsets or not, at this point. I know it didn't OC PCI-e for any enthusiast-friendly chipset, but I'm not sure about south bridge functions and whatnot.

With that CPU, you are rally better off leaving it around 2.8, and getting a new one ASAP, or finding a cheap A64 X2 BE CPU; or, if your mobo supports them, a cheap Phenom II BE. Black Editions have unlocked multipliers, so you can leave HTT at 200MHz.

 

[Davste]

I didn't know that. I'll leave it at 2.8 then. One more thing, if I unlocked overdrive from the CCC, I didn't void my warranty did I? I had reinstalled windows (and the CCC driver obviously). It was still unlocked.

 

[Bill Brasky]

To be clear, you are not overclocking your video card by increasing the mobo fsb. For the sake of simplicity, increasing fsb will only affect the CPU and RAM speeds, not your video card. Do not overclock the hyper transport or pci-e bus. Those should be left at stock and have settings completely separate from the fsb.

To overclock your video card, you will need to download a separate utility called msi afterburner. This is a utility used in windows that can modify gpu core clocks, vram clocks, gpu fan speed, etc.

 

[Davste]

To be clear, you are not overclocking your video card by increasing the mobo fsb. For the sake of simplicity, increasing fsb will only affect the CPU and RAM speeds, not your video card. Do not overclock the hyper transport or pci-e bus. Those should be left at stock and have settings completely separate from the fsb.

To overclock your video card, you will need to download a separate utility called msi afterburner. This is a utility used in windows that can modify gpu core clocks, vram clocks, gpu fan speed, etc.

Do you know what AMD overdrive is? Why should I download msi afterburner when I already have that functionality in CCC? Good to know I'm not overclocking my video card.

 

[Bill Brasky]

Do you know what AMD overdrive is? Why should I download msi afterburner when I already have that functionality in CCC? Good to know I'm not overclocking my video card.

Good question. I shouldn't have worded my sentence so matter of factly. AMD overdrive is ok, but msi afterburner allows for higher gpu core overclocks and has a wider range of features. I simply like that it supports very specific fan speed profiles, which allows better cooling at load and a more quiet fan at idle.

This is just an example from google, but I have my idle speeds at 11% and a more steep curve at 70C which is currently my max temp during gaming. MSI Afterburner allows for 8 points to be specified on the curve.

 

[Wallywest]

I used this as reference when I tried overclocking my Sempron 140:
http://www.ocia.net/articles/k10overclock/page1.shtml

I'm sure it'll answer some of the questions that you have regarding OCing the bus.

 

[kmmatney]

raising the FSB will not overclock the video card, but it can overclock the HT link speed, and cause a lot of weird things. There should be an option in the BIOS to change the HT linked speed multiplier (or something like that - it's always worded differently in different BIOSes). You can adjust it to lower the HT speed, and see if that helps. The HT speed affects the communication link between the CPU and video card, so it can effect the video indirectly. The link above has a good section on the HT speed.