7800GT and Direct3D shadow problem

[Loki91]

o..k... where to start? i suppose i'd want to say 'hi' first since i am new here, and also sorry since i come with an annoying dilemma

as the title suggests, im having slight problems with my Leadtek 7800GT. i have done some troubleshooting and have knocked it down to this:
my 7800GT is having problems displaying blended shadows in Direct3D. what happens is that i get extremely jittery shadows that are highly pixelated. i have done my research and it's because it wont 'blend' the shadow properly. i have noted this problem occur in both 3Dmark05, Guildwars and Need for Speed Most Wanted, and im pretty sure it'll appear in other Direct3D applications and games. i know that this shadow problem does not apply to OpenGL as i have tested Doom3, and all shadows run very smoothly (as expected with my 7800GT).

this isnt an out-of-box problem. a week or two ago i tried o/cing my GPU. using the coolbits registry hack, i upped my 7800GT from 400-1000 to 480-11xx (forgot specific memory clock). this of course seems like a crazy way to push, but detecting optimal frequencies gave me 476-11xx, and instruction from peers told me to increase it just a bit more. this caused serious artifacting in 3Dmark05, which made me return my card back to stock frequencies. since then i've been having this direct3D problem, and i am seriously distressed.

things i've tried:
trying out multiple nvidia drivers (81.95, 81.98, 83.10 (beta from Leadtek))
altering multiple options in rivatuner
making sure i'm back on stock frequencies
trying to detect artifacts with ATiTool (no artifacts detected for 1 hour+)
making sure i have DirectX 9.0c installed

things that i havent tried:
reinstalling windows etc (reluctant to do so as i have plenty of data on my computer and have no effective way of backing it all up)
reinstalling the entire GPU to check for connection problem (i doubt this would be the problem, correct me if im wrong)
doing anything advanced to check whats happening to my Direct3D

things that may have a hand in the matter:
the box that my 7800GT came in said that i needed a PSU with a 20A rating on the 12v rail, but since my PSU uses dual 12V rails, each rail only supplies 18A
it MAY be possible that something under the GPU fan or some other part of the GPU isnt functioning properly
nvidia uses temp monitoring and will kick the clock down if excessive heat is achieved. perhaps something like that killed the direct3D?

i guess that pretty much sums up what's wrong. i'd greatly appreciate feedback and DEFINITELY solutions if u have any.

(btw im using an Enermax WhisperII 535W model if u think somethings wrong with my PSU)

 

[CP5670]

There is a big thread on this issue here, which has been observed in Far Cry and some other games too:
http://forums.anandtech.com/messageview...atid=31&threadid=1699680&enterthread=y

I haven't noticed any different behavior from overclocking though. I get this blocky shadow effect on my current cards but also had it on a 6800GT and even my old Geforce 3, using a variety of drivers. I wonder if the coolbits edit itself does something. In some games it seems to occur on ATI cards too while others games look right on those cards, so there may be more than one issue here.

 

[dug777]

as cp said, the issue has been noted in farcry and some others, i saw that in NFS:MW (but i've no idea what the shadows SHOULD look like). AFAIK the 3dmark problem is due to nvidia's use of DST...

 

[Loki91]

perhaps the funny thing is that i began seeing shadow problems only after approximately an hour of play in NFSMW (i only got it yesterday).
also, does this mean that many highend GPUs are falling under this condition? its very disturbing to know that such expensive equipment hasnt been tested properly.
btw is it possible for future drivers to completely fix this problem? or is something just wrong with the hardware?
sorry to raise so many questions, but does the z-buffer have anything to do with this?

oh and thx for the replies. good to see that im not the only one with the problems.

 

[nts]

see here

Its probably a worse case of the above.

 

[Loki91]

umm... doesnt that article outline how ATi cards are unable to use DST to better render shadows in 3Dmark05? my problem here seems to be with an nvidia card and its handling of direct3D...
oh and i'd like to ask again: is this kind of problem solvable with newer directx/gpu drivers?

 

[nts]

Originally posted by: Loki91
umm... doesnt that article outline how ATi cards are unable to use DST to better render shadows in 3Dmark05? my problem here seems to be with an nvidia card and its handling of direct3D...
oh and i'd like to ask again: is this kind of problem solvable with newer directx/gpu drivers?

Its basically the same thing AFAIK, except in games your shadow map resolution will be quite a bit smaller and this will magnify the results.

ATi cards handle the shadow map filtering in the shader and with some tuning can produce very nice results. NVIDIA handles it with a low quality filter on the hardware directly, its fast but the quality suffers.

Solvable with new drivers, maybe if they shader replace the code for a high quality filter but that is not going to happen. As you saw from the above article, NVIDIA cards take a pretty big hit from disabling the onboard filter. Its not a feature of DX, only supported on NVIDIA cards and covered with a patent (stupid for a basic filter but whatever...)

btw post a screenshot, easier to tell what the problem might be (if I'm guessing at the wrong thing)