Can't change Graphics settings when using mat_dxlevel 98

[SocMinarch]

Processor: Intel Core 2 Duo E8200 2.66GZ 2.67GZ (That's what Windows says)
RAM: 2GB
GPU: NVIDIA GeForce 8400GS 256MB
OS: Windows 7 Ultimate

Addons:
Wire Mod (Full with Extras)
Stargate
DepthHUD Radar
Joystick
Jumper V3
Nuke Pack 4
PC Mod 2
SharpeYe
Smartsnap
Replicator
T-Rex

When I try to change my Advanced Video Settings while having +mat_dxlevel 98 in Advanced Launch Options, Garrys Mod just crashes. I have the same problem in TF2 (Strangely, it's fine in Alien Swarm).

[SocMinarch]

-bump-

[tratzzz]

You don't need to use DX98. Use 95 and you are okay.

It is possibly only experimental, not finished yet.

[SocMinarch]

[QUOTE=tratzzz;26183713]You don't need to use DX98. Use 95 and you are okay.

It is possibly only experimental, not finished yet.[/QUOTE]
DX98 used DX10 Shader Model.

[DatMeg]

It seems you cannot change graphics settings if there is anything in the command line.