XFX 7900 being sneaky with delta clocks

[eva2000]

Hmmm XFX might not be clocked as high in real 3D mode http://forums.guru3d.com/showpost.ph...postcount=1172 ?

i have been looking into the bioses of a few of the 7900 series cards and the 7900gts, all the gts i have seen run at 1.2 volt in the bios where as gtx runs at 1.4 so i am sure when the bios is modded to 1.4 on the gts with adequate cooling of course it should in theory be able to reach a similar level on the core as gtx, the weirdest thing i saw is on the delta clocks in the cards bios my msi 7900gtx has a 50mhz value on all 3 vid values whereas the 7900gt by xfx has 0 on all values on the delta clocks and the xfx 7900gtx xxx has 15mhz value on the delta clock of the core, whereas the msi 7900gtx has delta clock of 50mhz on the core, i wonder if this is done to give them a higher core clock value, i don't know, i'd be interested to know what difference the delta clock values make

for those unfamiliar with delta clock or geometric clock on 7800GTX series they had a 40mhz delta clock so for example BFG 7800GTX rated 460/1300 in 3d mode would be 500/1300 and drop back to 460/1300 in 2d mode.

With 7900GTX, MSI has 50mhz delta while XFX 7900GTX XXX has a 15mhz delta.

If MSI 7900GTX stock core is 650mhz then 3d = 700
If XFX 7900GTX XXX stock core is 675-690mhz then 3d = 690-705mhz

so in 3d mode it might end up the same clocks!!!!!

Interesting to see what other 7900GTX brands have for a delta clock value!

[metro.cl]

interesting

[eva2000]

yeah wonder if eVGA 7900GTX SC locking issues might be due to the delta value ??? 690mhz + 50mhz = 740mhz on core if they had 50mhz as delta like MSI

[andL64]

so in fact these higher clocked cards arent any better than the others because theres a less or no delta instead of the 40 or 50 whatever... thats sucks all promotion....

[lawrywild]

for those unfamiliar with delta clock or geometric clock on 7800GTX series they had a 40mhz delta clock so for example BFG 7800GTX rated 460/1300 in 3d mode would be 500/1300 and drop back to 460/1300 in 2d mode.

With 7900GTX, MSI has 50mhz delta while XFX 7900GTX XXX has a 15mhz delta.

If MSI 7900GTX stock core is 650mhz then 3d = 700
If XFX 7900GTX XXX stock core is 675-690mhz then 3d = 690-705mhz

so in 3d mode it might end up the same clocks!!!!!

Interesting to see what other 7900GTX brands have for a delta clock value!

that's not actually what the delta clock is.

basically 7 series cards have 4 different clocks, geometric core clock, shader core clock, ROP core clock and memory clock.

the shader and ROP run in 3d at whatever you clock them to in coolbits etc. (though they only have speedbumps every 27mhz.)

the geometric core clock is the one thats affected by the delta, it's basically the above clocks + the delta value. the geometric core clock doesnt clock in 27 mhz steps though, which is why you will see a minor increase in speeds even without going up in 27mhz steps.

[mascaras]

EVA2000 so why the high scores in 3dmark????

for example:
if it was like you say so a XFX 7900GT cloked at 565/1800 the real cloks are (= +- 550/1800 )

and other 7900GT card like MSI at 550/1800 n fact its same as a XFX at 565/1800 and if is like that why if you run a 3dmark 2005 with MSI at 550/1800 you only get +- 9800marks and with a XFX at 565/1800
you get 10020maks ???


i think thats make no sense

[arisythila]

How do you check the delta on your card? I'd be interesed to see what mine is.

~Mike

[Vapor]

The ROP/Shader clocks are what matter the most, that's why.

I know on my 78GTX, my core could do either 600+50, 625+25 or 650+0 and it was all equally stable....but any higher on the geometry clock and it became unstable. This wasn't a big deal though as the ROP/Shader clocks are the most important, so I ran 650+0 for the highest scores. I never tried a negative delta (idk if it's even possible).

IMO...the shader clocks are what sell the card, the geom clocks are just gravy if you can get it to scale well

[arisythila]

I just checked mine in Nibitor.

my stock speed is 650/1600 with a 50mhz delta
The EVGA runs 690/1760 with a 50mhz delta aswell.

Some information for you, I hope it helps.

~Mike

[mascaras]

what version of nibitor your using???

[arisythila]

2.7

[mascaras]

in nibitor mine say geometric delta clock ---- 0

[Vapor]

GTs are supposed to have a 0-13MHz delta and GTXs are supposed to have a 0-50MHz delta, depending on the brand and stock speeds.

[mascaras]

XFX 7900GT Extreme stok speeds (520/1500) ---Geometric delta = 0

[arisythila]

This maybe why Im only able to do 697 tops. thats about 747 after the delta. I wonder if lowering it to 0 would yield any benefits.

[Vapor]

This maybe why Im only able to do 697 tops. thats about 747 after the delta. I wonder if lowering it to 0 would yield any benefits.

Try lowering it to 0....if it still doesn't respond, your ROP/Shader clocks are what are limiting you, so raise the delta (experiment with this)

[GoriLLakoS]

@eva2000 ...can you give the link of the full thread over guru3d???

[perkam]

Kunaak's going to be ALL over this

Perkam

[Coroner Kyle]

Let me know if I understand this: You can control the amount of the 3D bump for Nvidia cards? So some of the OC factory cards are really not that OC'ed when in 3D? I am thinking about getting a 7900gtx and with this info it makes me wonder if it's worth getting the ones that are OC'ed.

[andL64]

what are u all talking bout whats the REAL specs with deltas with 7900GT/GTX?

cant be that there are variable deltas between 0-50mhz must be a spec?!

lol

EDIT. here on the 7800GTX 256Mb (stock 430/1200mhz version) its 3D +50delta, 3D-throttling +45delta and 2D +0 delta
there must be such fixed specs 4 the 79GT/GTX

[Vapor]

eVGA/XFX/BFG etc. control the clocks, including the delta. Each part number has a different set of clocks and deltas.

nV recommends 650+50 and 450+12.

It is absolutely worth getting the OC'd ones.

[andL64]

eVGA/XFX/BFG etc. control the clocks, including the delta. Each part number has a different set of clocks and deltas.

nV recommends 650+50 and 450+12.

It is absolutely worth getting the OC'd ones.

ok, thx so its 700/462 3D delta

yeah with air its sure worth but with real xtreme cooling and ocing it really doesnt matter as far as i know.

[zakelwe]

that's not actually what the delta clock is.

basically 7 series cards have 4 different clocks, geometric core clock, shader core clock, ROP core clock and memory clock.

the shader and ROP run in 3d at whatever you clock them to in coolbits etc. (though they only have speedbumps every 27mhz.)

the geometric core clock is the one thats affected by the delta, it's basically the above clocks + the delta value. the geometric core clock doesnt clock in 27 mhz steps though, which is why you will see a minor increase in speeds even without going up in 27mhz steps.

Good summation.

The first guy at guru3d said he had a delta on "all 3 vid values" which is impossible as a delta means a change from the standard.

core\geometry+15\rops

would be a delta of 15, having all at +50Mhz would mean a delta of zero.

Can anyone actually tell me what he is saying when he says :-

"the weirdest thing i saw is on the delta clocks in the cards bios my msi 7900gtx has a 50mhz value on all 3 vid values whereas the 7900gt by xfx has 0 on all values on the delta clocks and the xfx 7900gtx xxx has 15mhz value on the delta clock of the core"

in plain English ?

Why do I get the feeling Unwinder is going to rip him a new large one ?

Regards

Andy

[[XC]Atomicpineapple]

possibly he means in 3d, throttled, and 2d modes?

[Richteralan]

Basically those pre overclocked 7900GT all have their GDC disabled. That's why they can be factory defaulted to such high frequency.

My BFG 7900GT OC has 20MHz GDC.