Overclocking 8x00 Shader Clocks Independantly of GPU Core Speed

555BUK · 5 Oct 2007 at 17:23

I have just been playing with the lastest version of Riva Tuner (V2.05) on my 8600GT (this applies all 8x00 cards) and noticed you can now move the shader slider independantly of the core.

Until now I have been stuck at 648core / 1700mem with the shader clock fixed at 1404. With the new version of RT I can get the shader clock up to 1620 stable and it does make quite a difference to benches. The 3DMark series give between 5-7% overal score increase with Company of Heroes bench giving 4%. Apparently this only works with recent NVidia drivers (from 163.63 onwards) so we can thank NVidia for enabling the functionality. Strange we have only been allowed to OC this way now that ATI have released reasonable competition - perhaps NVidia have been holding a thing or two back.

I imagine on 8800 GTS cards this will allow NVidia to keep up with / jump ahead of overclocked 2900's in many games.

TONY · 5 Oct 2007 at 17:35

So this takes away any real advantage there was from owning an 8800 Ultra?

555BUK · 5 Oct 2007 at 17:41

TONY said:
So this takes away any real advantage there was from owning an 8800 Ultra?

No, the ultra has additional hardware and also benifits from the above tweaks. It would take a severely overclocked GTS to match an Ultra at stock.

steve258 · 5 Oct 2007 at 17:42

Sorry if it's a bit ot but is the stream processors' speed on 2900 synchronised with the core speed? So whenever you oc the GPU you also oc the stream processors as well?

Greebo · 5 Oct 2007 at 17:42

TONY said:
So this takes away any real advantage there was from owning an 8800 Ultra?

I never thought there was any real advantage in owning a 8800 ULtra. To me they were like the BFG and EVGA pre-overclocked 8800 GTS cards. You can pay to have a guaranteed overclock or buy a normal one and hope you get a good one.

Greebo · 5 Oct 2007 at 17:43

555BUK said:
No, the ultra has additional hardware and also benifits from the above tweaks.

Didn't realise that.

Ignore my previous post then. Actually I have just had a quick look at the listings on ocuk and the only difference listed is the higher core and memory speeds as far as I can see so perhaps you can enlighten me as to what the additional hardware is please?

555BUK · 5 Oct 2007 at 17:50

Greebo said:
Didn't realise that. Ignore my previous post then. Actually I have just had a quick look at the listings on ocuk and the only difference listed is the higher core and memory speeds as far as I can see so perhaps you can enlighten me as to what the additional hardware is please?

Ultras and GTX's have 128 stream processors and 384bit memory interfaces versus 96 and 320 on the GTS. If you run all 3 at the same clock speeds the GTX and Ultra will give equal performance and the GTS will be ~15% slower in most apps.

Greebo said:
I never thought there was any real advantage in owning a 8800 ULtra. To me they were like the BFG and EVGA pre-overclocked 8800 GTS cards. You can pay to have a guaranteed overclock or buy a normal one and hope you get a good one.

The Ultra has better ram and better A3 revision cores but it is not woth £100 extra.

Greebo · 5 Oct 2007 at 17:53

555BUK said:
Ultras and GTX's have 128 stream processors and 384bit memory interfaces versus 96 and 320 on the GTS. If you run all 3 at the same clock speeds the GTX and Ultra will give equal performance and the GTS will be ~15% slower in most apps.

SOrry, my question was what were the hardware differences between a GTX and a ULtra, not a GTS

Kanifee · 5 Oct 2007 at 18:14

yeh been messing around with the new riva tuner and got my shader sitting @ 1650mhz
i refuse to use ati tool though as i have had a few problems with it so not sure if that can go higher.

NaNd0! · 5 Oct 2007 at 18:33

I've been clocking the core independant to the shader on my 8600gt.. however i cant seem to exceed 675mhz! Even 676mhz wont save using riva tuner... as soon as press ok it drops back to 675mhz. Any ideas on that one?

Cyber-Mav · 5 Oct 2007 at 18:39

NaNd0! said:
I've been clocking the core independant to the shader on my 8600gt.. however i cant seem to exceed 675mhz! Even 676mhz wont save using riva tuner... as soon as press ok it drops back to 675mhz. Any ideas on that one?

whats your shader clock speed at? is it linked to core speed? or you running it at a different speed?

555BUK · 5 Oct 2007 at 20:23

Just done a few benches with my 8600GT at the following clocks.

core shader mem
648 / 1404 / 1700 (standard shader value 1404 @ 648 core)
648 / 1620 / 1700 (max stable shader value)

shader 1404 / 1620
3DMARK01 37227 / 38484 +1257 (+3.4%)
3DMARK03 19359 / 19922 +563 (+3%)
3DMARK05 11427 / 12028 +601 (+5.3%)
3DMARK06 5510 / 5837 +327 (+5.9%)
COH 43.20fps / 45.05fps +4.3%

COH - Company of Heroes @ 1680x1050 and mixture of Med+High settings (my prefered res).

Cyber-Mav · 5 Oct 2007 at 20:51

hmm, 06 shows the biggest speed increase.

is 1620 the max shader speed you can get? what happens if you go higher?

555BUK · 5 Oct 2007 at 21:06

Cyber-Mav said:
hmm, 06 shows the biggest speed increase.

is 1620 the max shader speed you can get? what happens if you go higher?

The next step up in shader clocks is to 1674, but one of my benches froze at this speed so I backed it down.

default shader clock (when core is at stock) is 1188 so we are talking a 40% jump. The core and memory on my card only give an extra 20%, but I have passive cooling so they may be getting hot.

sunderland · 5 Oct 2007 at 21:16

have you tried ati tools with the shader clock as i benched my 8800gtx at 1600 in 3dmark06 3 times of the trot and all was ok but when i did a artifact test in tools it would only go to 1480 then i would get errors every so many seconds,

PinkFloyd · 5 Oct 2007 at 23:06

Am I being really blond or something?
I'm running the 163.711 drivers with rivatuner 2.05 and I can't see where to change the shader clock? I can see the core and memory clocks though.
Is there something I have to enable first?

C64 · 5 Oct 2007 at 23:12

on xp? ok you need to look at this
http://www.guru3d.com/newsitem.php?id=5958 i have no idea where to put mine currently at 621/864 shader at 1404 must be fine just played crysis for 2 hours.

PinkFloyd · 5 Oct 2007 at 23:45

Worked great dude, will get some benchmark results up later.

Cyber-Mav · 6 Oct 2007 at 03:57

555BUK said:
Just done a few benches with my 8600GT at the following clocks.

core shader mem
648 / 1404 / 1700 (standard shader value 1404 @ 648 core)
648 / 1620 / 1700 (max stable shader value)

shader 1404 / 1620
3DMARK01 37227 / 38484 +1257 (+3.4%)
3DMARK03 19359 / 19922 +563 (+3%)
3DMARK05 11427 / 12028 +601 (+5.3%)
3DMARK06 5510 / 5837 +327 (+5.9%)
COH 43.20fps / 45.05fps +4.3%

COH - Company of Heroes @ 1680x1050 and mixture of Med+High settings (my prefered res).

your 3dmark 05 score is higher than my x1900xt score in 3dmark 05, max i ever got was 11103 in 3dmark 05, and i got 5880ish in 3dmark 06.
your 8600gt is rapid :eek:

V|per · 6 Oct 2007 at 06:54

Greebo said:
SOrry, my question was what were the hardware differences between a GTX and a ULtra, not a GTS

555BUK said:
The Ultra has better ram and better A3 revision cores but it is not woth £100 extra.