Rivatuner shows me a range of +/- 3.0, does the program you're using have a different range for LOD values? I've been using older drivers, at latest 169.21.
I thought perhaps the 101.09 driver that I was using might be the reason why LOD adjustments weren't doing anything, so I tried 169.21. The LOD adjustments are immediately obvious, because the picture is blurry, including loading screens. However the score is no different. In 101.09 the LOD adjustments didn't visibly change the picture at all.
169.21 Control
raw
sorted
0
1300
1294
Best half average
Best half range
1
1297
1295
1298.0
3.0
2
1295
1295
3
1297
1296
4
1297
1296
5
1299
1296
6
1297
1296
7
1296
1297
8
1296
1297
9
1299
1297
10
1295
1297
11
1297
1297
12
1294
1298
13
1298
1299
14
1296
1299
15
1296
1300
Clamp negative LOD bias, and +1.5
0
1297
1295
Best half average
Best half range
1
1299
1296
1298.6
1.0
2
1296
1296
3
1297
1296
4
1296
1297
5
1299
1297
6
1299
1297
7
1295
1297
8
1296
1298
9
1298
1298
10
1298
1298
11
1297
1299
12
1299
1299
13
1297
1299
14
1298
1299
15
1299
1299
Then I tried checking the "Color mipmaps" option in 3DMar05 settings, as well as setting LOD bias to +2.5 in Rivatuner, and that resulted in a significant improvement in score, but the benchmark is rendered not sampling the color textures, but solid colors representing the LOD mipmaps or something. Is that tweak allowed?