7800 series Key Overclock Points

[sluflyer06]

Please note this information is courtesy of HeavyH2O on XtremeSystems. I know alot of us post on both forums but more of us don't and I've found this information very useful and have confirmed this with my own testing.


After some testing, the best points on the core clock of the nVidia 7800 series cards are whole multiples of the core frequency oscillation of 27 MHz. That calculates to the following root core clocks:

(17 x 27) - 40 = 419
(18 x 27) - 40 = 446
(19 x 27) - 40 = 473
(20 x 27) - 40 = 500
(21 x 27) - 40 = 527
(22 x 27) - 40 = 554
(23 x 27) - 40 = 581

And, here is how a single MHz below the whole number threshold affects 3Dmark05 scores:

445 8052
446 8222

472 8404
473 8508

499 8669
500 8753

Now, what about the other two cores. How are those controlled?

Well, when you adjust the root clock, you actually adjust all three clocks.

The root clock gets bumped by 40 MHz to represent the real geometry or vertex core clock. So, lets pick 450 core, which so many vendors use. 486 is the best vertex clock value (18*27), which translates to 446 root (486-40). So, we would actually have 490 using a 450 root clock, a 4 Mhz pad on the required frequency.

But, the shader and ROP cores start at 415 (really 418.5) in low power, and jump in whole frequency values (ie, 17 x 27 = 459) to a value that is less than 13.5 MHz over or equal to the root frequency. In this case the root frequency is 450 which is 18 MHz over 432 (16 x 27) and 9 MHz shy of 459 (17x 27), so 459 is the ROP/Shader clock.

So, a little confusing, but you do have some control over the other two clocks.

So, here is a list of primary - vertex based (red) and secondary - ROP and shader based (blue) root clock OC targets. The red will yield the larger gain, and you will see a second, albeit smaller gain on the blue clocks where the optimal memory frequency matches the root clock.

419
432 - the nVidia spec root clock
446 - so many vendors use 450
459 - why BFG uses 460
473
486 - why eVGA, XFX, and BFG use 490 on limited cards
500
513
527
540 - How I got 9539 on 3DMark05 with a lowly 3200+ and one 7800 GTX
554
567
581
594
608
621

[BIOHazard87]

great thread, only if u made one for 6800 series :P

[eboy0]

Originally Posted by BIOHazard87

great thread, only if u made one for 6800 series :P

The 6 series doesn't work like the 7 series AFAIK, this is only regarding the 7 series, mainly because of ROP clock i believe.

[BIOHazard87]

rawr, 6 series would get some better combonations... like here are some results i got with FarCry benchmark:


57.27 - 392/1.09
57.84 - 404/1.09
59.36 - 392/1.10
60.00 - 400/1.10
60.19 - 404/1.10

[Tim]

yep very nice, it's also on XS

[sluflyer06]

not to be rude, but did you read the big bold letters at the top of the post stating the original poster on XS where i got it?

[ether.real]

can you highlight the numbers that should be in Red? That would be nice


Thanks

[delas52]

So, basically the numbers that have had 40 subtracted from them is what I want to aim for in coolbits (419, 446, 473...), right?

[Tankmanbob]

Great post - I ended up with 486 core through trial & error, its nice to know its not a coincidence.

Is there a similar guideline for the memory setting? I'm sitting at 1380 which works fine for all the benchmarking, but starts to get a bit overwhelmed after a few hours of Half Life 2.

[qwerty]

sticky the thread?

[Tim]

Originally Posted by sluflyer06

not to be rude, but did you read the big bold letters at the top of the post stating the original poster on XS where i got it?

lol take it easy...I just said that it was also at XS...nothing more nothing less...

[qwerty]

Sorry, but can this useful thread be stuck?

[Sandman]

Sticky this gem . Maybe add the same type of guide for the mem clock (if you can), it would help us OC newbs a bunch

[skilltim]

sluflyer06 do you realise you have the highest score in 3Dmark05 for this forum...

http://forums.extremeoverclocking.co...d.php?t=167500

Add your name here for some

[Tim]

Originally Posted by qwerty

Sorry, but can this useful thread be stuck?

PM a mod...but before that...do this :

So, here is a list of primary - vertex based (red) and secondary - ROP and shader based (blue) root clock OC targets. The red will yield the larger gain, and you will see a second, albeit smaller gain on the blue clocks where the optimal memory frequency matches the root clock.

Red and Blue overclock points....copy it the right way

[chrisshort]

i like this little guide. i lost it for a while took me ages to find again!

[skilltim]

Please could you tell us what the core frequency for geforce 4 and 5's are?

[rahzel]

im a little confused. ive read the thread at xtremesystems.org where Heavyh20 posted this info several times. people are discussing that the GT has different key points.

Also, HeavyH20 says that having a lower clock with a geometric clock performs better than higher clock without a geometric clock.

well, my max clock speed is 459/462 (around there. setting it to 462 bumps it up to 464mhz) without a geometric clock. I tried modifying my BIOS so it would have a clock of 419mhz + a 45mhz geometric clock (making it 464) and my 3dmark05 score was about 200 points less compared to when i had it at 462 without a geometric clock.

according to HH20, its supposed to be higher isnt it? or am i looking at this the wrong way?

[delas52]

Originally Posted by rahzel

im a little confused. ive read the thread at xtremesystems.org where Heavyh20 posted this info several times. people are discussing that the GT has different key points.

Also, HeavyH20 says that having a lower clock with a geometric clock performs better than higher clock without a geometric clock.

well, my max clock speed is 459/462 (around there. setting it to 462 bumps it up to 464mhz) without a geometric clock. I tried modifying my BIOS so it would have a clock of 419mhz + a 45mhz geometric clock (making it 464) and my 3dmark05 score was about 200 points less compared to when i had it at 462 without a geometric clock.

according to HH20, its supposed to be higher isnt it? or am i looking at this the wrong way?

Just without messing with your BIOS use the highest stable OC. It's much easier and generally yeilds better results. These points are just for if you can only get like 2 mhz more over one of them just to drop the OC to the key point.