View Full Version : BFG 6800OC core won't OC w/ extra pipes

12-05-04, 11:06 PM
Cliff's Notes:
1. BFG 6800OC overclocks fine with 12/5
2. Unlock the extra pipes to 16/6, now can only OC the RAM
3. What to do?

Let me start by saying I read the stickied thread about the 6800 OCing, but I think my question is slightly different.

I recently got a 128MB BFG 6800OC. It overclocks fine with at the stock 12/5; I had it set to 400MHz core and 870MHz RAM. I could overclock it in the drivers with coolbits or with RivaTuner with no problems. When I look at my system properties in 3DMark 2003, it properly reports the speeds at 400/880 (or whatever I set it to).

I have successfully unlocked the extra pipes via RivaTuner. Now when I OC in coolbits, I get the "The test failed to run at the specified clock frequencies" error. So I changed the DisableInternalClockTest setting. After doing that, I still couldn't overclock (or even underclock) in coolbits, but RivaTuner seemed to be working fine. Until I checked 3DMark properties that is...

With the extra pipes enabled and internal test disabled, it seems I am only able to OC the RAM. I set it back to 400MHz core and 870MHz RAM and in 3DMark it shows it as 350MHz (stock for the 6800OC) and 870MHz RAM. The core speed never changes; no matter what I set it to in RivaTuner it always shows as 350MHz, though the RAM speed is displayed properly. I verfied this by running various benchmarks at different core speeds and the scores always came back the same.

I've tried a few different driver versions, PowerStrip, disabling fast writes, and I still can't change the core speed. Is there anything I can do to be able to change the core speed? TIA. Specs below:

WinXP Pro SP2
P4 3.2E @ 3.6GHz
128MB BFG 6800OC (currently with 66.93)

12-05-04, 11:12 PM
This is normal, many 6800s cant overclock after unlocking the pipes. Lets do a fill rate check to see which is better though.

12x400 = 4800 megapixels / second
16x350 = 5600 megapixels / second

The higher fill rate will really help out in shader heavy sitations. Also, with the extra pipes unlocked you have matched the 6800GT in fillrate.

12-05-04, 11:25 PM
Thanks for the reply. Yeah, it's a little faster.

CS:S stress test, 1024x768, everything on high except reflect world instead of reflect all:

12/5 400/870
No aa/af: 135.85FPS
4xAA/8xAF: 106.50FPS

16/6 350/870
No aa/af: 138.50
4xAA/8xAF: 111.96FPS

I'd sure like to have 400MHz and 16 pipes though, haha. So there is no way to work around it with pipes enabled?

edit: also it's weird that I can't even underclock it, so I'd imagine that there is something forcing it to run at the stock 350MHz. BIOS I'd assume...

12-06-04, 02:06 AM
I have a leadtek 6800 and it overclocks very well with the pipelines unlocked. I could push it past 375/875. I could actually get it at 385/885 but I get very tiny artifacts once in a while. Besides I'm ashamed to say its paired with an Athlon 2800+ Barton so pushing higher may not help much.

12-06-04, 03:05 PM
My leadtek 6800 is unlocked perfectly and still overclocks nicely to 380/900 Works fine. So unknown what your problem is. Maybe vendor specific fault.