Slowdowns from overclocking Radeon 9800 core?

[Leo V]

I got my ATI Radeon 9800np (non-Pro) last night. Everything is working great, but when I try to overclock it, I encounter a disturbing trend:

As soon as I overclock the core (using either Powerstrip or RadLinker), the card slows down in several benchmarks. In particular, 3dmark2001 vertex throughput drops WAAYY down from 75mtriangles to 30mtriangles. And MS DX9 Water demo drops from 90fps to 25fps. Returning the clockspeed to normal or rebooting doesn't fix this! I have to reinstall ATI's drivers to get back the "good" scores!

This problem only comes from adjusting core speed, I adjust mem speed with no problems. Any ideas what's up?
Thanks!~
Leo

 

[Nebor]

I would imagine it would have something to do with running the processor and memory in synch.

 

[pelikan]

Video cards perform better when you overclock them until they are pushed too far. Often the first sign of pushing them too far is decreasing performance, even before you see artifacts or screen locks. It's best to go 5MHz at a time and benchmark along the way so you can find the sweet spot.
Maybe your card doesn't have a very overclockable core.
You could try flashing it to a pro bios. That might help. But make sure you get a bios with reduced clocks. It would not be very fun to flash to a speed you cannot boot from.

 

[PepperDog]

After reading this message I did a little testing of my new 9800NP. As I suspected, I've experienced almost the exact same problem. What a bummer... I hope I haven't ruined my new vid card

 

[Hankysmoo]

What ram does your Radeon 9800 have?

 

[BudAshes]

I think you have to flash them to hacked 9800 pro bios to overclock some 9800's.

 

[PepperDog]

Well cripes. I seem to have discovered my problem. Freakin 6xAA and 16xAF will certainly lower benchmark scores! Doh. Stupid me forgetting I had those settings.

Anyways, Leo, as stupid as it sounds, make sure you check your AA/AF settings before benchmarking. I got so used to them I forgot I even had em. Sighs of relief as everything is back to normal here.

PD

 

[Leo V]

So far, I got around the problem by jumping by 5mhz and immediately rechecking both benchmarks. So far I got to 365 mhz core with no problems at all. Maybe jumping too quickly causes the problem.

Right now, I have no electricity in the wake of the hurricane. I'l resume investigating once I get power.

 

[Leo V]

Originally posted by: PepperDog
Well cripes. I seem to have discovered my problem. Freakin 6xAA and 16xAF will certainly lower benchmark scores! Doh. Stupid me forgetting I had those settings.

Anyways, Leo, as stupid as it sounds, make sure you check your AA/AF settings before benchmarking. I got so used to them I forgot I even had em. Sighs of relief as everything is back to normal here.

PD

Hmm.. well I'm pretty sure I wasn't playing with AF/FSAA while overclocking. If I was, the difference I observed would be in different (fillreate-limited) benchmarks. But the impending hurricane could have warped my reasoning..