Question on why unlocking 6950 shaders would impact one game only

[NTAC]

Just looking for some logical explanation.

I unlocked the shaders on my 6950 cards, and I can play BF3 for hours and hours with no issues.

When I try to play Madden 08 PC however, I usually can't get through a single game without a BSOD.

I've locked the shaders back to original and now Madden is fine.

I don't really care that much to be honest, the shader unlock benefit is not really that big of a deal to me, but I'm mainly curious as to why an old and much less demanding game would trigger a BSOD while a state of the art game like BF3 would not...

 

[Silverforce11]

Turn on vsync on your Madden 08 and see if it BSODs (force via drivers if necessary).

 

[NTAC]

Turn on vsync on your Madden 08 and see if it BSODs (force via drivers if necessary).

Even if Madden 08 works perfectly fine without the shaders unlocked?

 

[Silverforce11]

Yeah try it and see.

 

[Tuna-Fish]

I don't really care that much to be honest, the shader unlock benefit is not really that big of a deal to me, but I'm mainly curious as to why an old and much less demanding game would trigger a BSOD while a state of the art game like BF3 would not...

The GPU shaders implement a lot of different instructions. One of your disabled shader clusters probably fails on one specific instruction (or a specific combination of instructions). For whatever reason, BF3 doesn't ever use that instruction, and Madden does.

This is *extremely* common with unlockable hardware. Especially so in the AMD cpu's that could be unlocked -- x86 has ~500 instructions, with a lot of weird special cases, and if the CPU core ever fails in any of those cases in any of those instructions, it's faulty and will be disabled. Of course, a lot of those instructions are vestigial remnants that will never actually be emitted by modern compilers and will probably only ever be executed by the test suites they use to validate the cpus. Which is why it often makes sense to unlock the cores.

This is why you can not adequately test stability with any one program, and especially not with any simple synthetic test. You need to test with all the programs you use.

 

[NTAC]

Ok, that does make sense. Thanks! I'll try teh vsynch thing as well next time I get a chance.