8800GTX Weird GPU/ROP Behavior

[ThePredator]

Well, It's simple, I have a eVGA 8800GTX, I am overclocking it to 621/1053. Here is the problem, the card will either go to 621 or 648, not in between. Same for the memory, it's either 1053 or 1080. I can not, no matter what I did, change the core or memory clock speed to anything in between them. I tried riva tuner, I tried the ATI Tool. And like you can imagine, the moment I go to 648 or 1080, the 3dmark06 won't even make it for 1 minute, it'll just freeze.

[Seinken]

Could be the shader that clocks along with it, not sure exactly of how it works...

[rainless]

That's probably just the memory/core strap. It's normal to not be able to do 1023... 1024... etc. Because those vaules don't really exist. Memory and core speed are increased in blocks not increments.

[ViperJohn]

Well, It's simple, I have a eVGA 8800GTX, I am overclocking it to 621/1053. Here is the problem, the card will either go to 621 or 648, not in between. Same for the memory, it's either 1053 or 1080. I can not, no matter what I did, change the core or memory clock speed to anything in between them. I tried riva tuner, I tried the ATI Tool. And like you can imagine, the moment I go to 648 or 1080, the 3dmark06 won't even make it for 1 minute, it'll just freeze.

That is normal for 8800's. The ROP and memory clocks will only step for sure on integer multiples
of 27Mhz (the clock generator crystal controlled base frequency). They will step on some 1/3 and
2/3's multiple of 27Mhz but not all.

The Shader clock only steps on integer multiples of 54Mhz.

Viper

[largon]

Here's a chart how 8800 -series core, shader and ram clocks go:

GPU clk:
527 = 540
554 = 567
572 = 576
585 = 594
604 = 612
617 = 621
635 = 648
662 = 675
680 = 684
693 = 702
712 = 720
725 = 729
743 = 756
770 = 783

Shader domain clk (bound to GPU clk):
<434 = 999
434 = 1026
455 = 1080
479 = 1134
502 = 1188
525 = 1242
540 = 1296
572 = 1350
595 = 1404
618 = 1458
642 = 1512
680 = 1566
688 = 1620
712 = 1674
735 = 1728
758 = 1782

RAM clk:
897 = 900
909 = 918
928 = 936
941 = 945
959 = 972
986 = 999
1004 = 1008
1019 = 1026
1036 = 1044
1049 = 1053
1067 = 1080
1102 = 1107
1111 = 1116
1129 = 1134
1147 = 1152
1158 = 1161
1183 = 1188

Feel free to continue fillling the chart if you get higher than these values.
At the moment my card maxed at the last figures for each section. ;)

[ViperJohn]

Here's a chart how 8800 -series core, shader and ram clocks go:

Feel free to continue fillling the chart if you get higher than these values.
At the moment my card maxed at the last figures for each section. ;)

Actually if you just use 9Mhz steps on the even, 1/3 and 2/3 mulitples of 27Mhz it is easier (just remember
some 1/3 and 2/3 multiples will not produce a clock speed change.

Also your Shader clock numbers, in relation to the ROP clock, will only hold on cards using the same
bios as the card you used to create the chart. The Delta between the ROP and Shader clocks and where
the shader clock steps in relation to where the ROP clock steps can be changed in bios and can/will be
different on the various OC version cards.

Viper