FSB affect on Video Card

[RedWolf]

When I set my FSB to anything above 140, my system becomes unstable. If I underclock my video card, things clear up. WHen the FSB is set to 133, my 8500 LE can run at about 275 core and 265 memory. The more I up the fsb, the slower I have to clock the video card to gain stability.

I'm running a 300 watt PS, 1 WD 80 SE, 2 cd drives, and 5 fans. Could this be a PS issue or is my video card just a poor overclocker?

 

[WaTaGuMp]

Could be that the FSB at 140 makes your AGP PCI bus go to high, which is not a good thing. Does your mobo have a AGP PCI lock feature in the bios if so lock it to 33-66 and try that.

 

[RedWolf]

It does not (have a bus locking feature). I can boot the machine with the 8500 clocked at 250 core and 200 memory with the fsb at 150. I can complete 3dmark at 148. The motherboard is an AK35GTR. The AGP bus runs at 74 mhz according to Sandra when I'm at 145-150.

 

[BigJ]

As you overclock your video card, it becomes more sensitive to changes in things, IE lower voltages, irregular frequencies, etc. The AGP bus being out of spec via you overclocking is absolutely causing the instability at higher speeds

 

[RedWolf]

So overclocking the fsb with this particular card is out then? With the GF2 I had, I could overclock both. Had things running stable with the fsb at 148. I was wondering about the power issue since I had upped the voltage and added an additional fan.

 

[BigJ]

Well decide whats more important to you. Do you want a faster video card or processor? In either case, overclock the one you want faster to its highest speed with the other being at default speed. Then slowly raise the other until your as high as you can get with the stability you demand.

 

[WaTaGuMp]

I say go for the highest fsb you can get cause its all about the fsb BABY

 

[Metalloid]

When you overclock the FSB you are overclocking the AGP bus also. Your card can only be overclocked so much. So wheter you do it by actually upping the cards Core and Memory frequencies, or by doing it when you increase the FSB, you are still overclocking the video card.

 

[RedWolf]

I think it is a problem with the power supply. I unplugged the dvd player, 3 fans, and my NewQ. Now, I can get the fsb up to 147 and overclock the 8500 ro 270 core, 265 memory. Not great overclocks on the radeon, but good enough. I was able to loop 3dmark for a few hours and things seem stable. When I plugged everything back in, I couldn't even complete the first test in 3dmark.

 

[movinslow]

A bit OT, just wanted to say nice sig Metalloid15!! I think I've had experience mixing those two...