Overclocking 8x00 Shader Clocks Independantly of GPU Core Speed

[555BUK]

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.

 

[555BUK]

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.

 

[555BUK]

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.

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.

 

[555BUK]

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).

 

[555BUK]

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.