As it stands, this is a bad idea. All you will do is very quickly make a 'shoot first to win' scenario out of every battle. A single attack will be often be lethal even if the victim makes the save.

Problems

A fireball of 6d6 averages 21 damage, assuming the caster hasn't raised his damage in other ways (not that they'd need to, in most cases). This means that any 6th-level wizard or sorcerer can AoE insta-kill most creatures - including player characters!

Also, meat-shields would no longer be effective, weakening tank classes, along with healing spells, and casters - especially those who can summon creatures - would become even more powerful.

Houserules to balance the game again

The only ways that spring to mind to balance this would be to hand out DR like candy, and/or have such high saves and armour class that the characters are untouchable - but a natural 20 will still kill in these cases. Overall, there's no good way to nerf character HP without also cutting down damage or expecting your players to resurrect or re-roll several times a session.

Best alternative

E6 seems like it'd work quite well. It stops your players from leveling past level 6, which would automatically limit their hit points. Instead, they get feats every 5000xp. This looks like it could replace the limits on player health, and then limiting monster health isn't as broken either since the player characters can't consistently cause, say, 30 damage (if you set the cap at 30 or higher, this would be a quite elegant solution).

Other alternatives

An alternative solution could be to replace HP with a more lethal system instead, or increase potential damage. Making all damage dice explode makes a dagger blow much more threatening, since you could roll several 4's in a row quite easily over the course of a long game. The stress tracks from FATE might also be more suitable, if you can find a good way to port them over. Lastly, consider switching to a system that places more emphasis on danger, such as Harnmaster (known for being both dangerous and simulationist).

tl;dr

You can't cap hit points in D&D 3.5 without seriously breaking the game, and there aren't really any ways to completely fix the problems you cause. Instead, look at capping monster hp and using the E6 system for the players.

As it stands, this is a bad idea. All you will do is very quickly make a 'shoot first to win' scenario out of every battle. A single attack will be often be lethal even if the victim makes the save.

Problems

A fireball of 6d6 averages 21 damage, assuming the caster hasn't raised his damage in other ways (not that they'd need to, in most cases). This means that any 6th-level wizard or sorcerer can AoE insta-kill most creatures - including player characters!

Also, meat-shields would no longer be effective, weakening tank classes, along with healing spells, and casters - especially those who can summon creatures - would become even more powerful.

Houserules to balance the game again

The only ways that spring to mind to balance this would be to hand out DR like candy, and/or have such high saves and armour class that the characters are untouchable - but a natural 20 will still kill in these cases. Overall, there's no good way to nerf character HP without also cutting down damage or expecting your players to resurrect or re-roll several times a session.

Best alternative

E6 (another link) seems like it'd work quite well. It stops your players from leveling past level 6, which would automatically limit their hit points. Instead, they get feats every 5000xp. This looks like it could replace the limits on player health, and then limiting monster health isn't as broken either since the player characters can't consistently cause, say, 30 damage (if you set the cap at 30 or higher, this would be a quite elegant solution).

Other alternatives

An alternative solution could be to replace HP with a more lethal system instead, or increase potential damage. Making all damage dice explode makes a dagger blow much more threatening, since you could roll several 4's in a row quite easily over the course of a long game. The stress tracks from FATE might also be more suitable, if you can find a good way to port them over. Lastly, consider switching to a system that places more emphasis on danger, such as Harnmaster (known for being both dangerous and simulationist).

tl;dr

You can't cap hit points in D&D 3.5 without seriously breaking the game, and there aren't really any ways to completely fix the problems you cause. Instead, look at capping monster hp and using the E6 system for the players.

As it stands, this is a bad idea. All you will do is very quickly make a 'shoot first to win' scenario out of every battle. A single attack will be often be lethal even if the victim makes the save.

A fireball of 6d6 averages 21 damage, assuming the caster hasn't raised his damage in other ways (not that they'd need to, in most cases). This means that any 6th-level wizard or sorcerer can AoE insta-kill most creatures - including player characters!

Also, meat-shields would no longer be effective, weakening tank classes, along with healing spells, and casters - especially those who can summon creatures - would become even more powerful.

The only ways that spring to mind to balance this would be to hand out DR like candy, and/or have such high saves and armour class that the characters are untouchable - but a natural 20 will still kill in these cases. Overall, there's no good way to nerf character HP without also cutting down damage or expecting your players to resurrect or re-roll several times a session.

An alternative solution could be to replace HP with a more lethal system instead, or increase potential damage. Making all damage dice explode makes a dagger blow much more threatening, since you could roll several 4's in a row quite easily over the course of a long game. The stress tracks from FATE might also be more suitable, if you can find a good way to port them over. Lastly, consider switching to a system that places more emphasis on danger, such as Harnmaster (known for being both dangerous and simulationist).

As it stands, this is a bad idea. All you will do is very quickly make a 'shoot first to win' scenario out of every battle. A single attack will be often be lethal even if the victim makes the save.

Problems

A fireball of 6d6 averages 21 damage, assuming the caster hasn't raised his damage in other ways (not that they'd need to, in most cases). This means that any 6th-level wizard or sorcerer can AoE insta-kill most creatures - including player characters!

Also, meat-shields would no longer be effective, weakening tank classes, along with healing spells, and casters - especially those who can summon creatures - would become even more powerful.

Houserules to balance the game again

The only ways that spring to mind to balance this would be to hand out DR like candy, and/or have such high saves and armour class that the characters are untouchable - but a natural 20 will still kill in these cases. Overall, there's no good way to nerf character HP without also cutting down damage or expecting your players to resurrect or re-roll several times a session.

Best alternative

E6 seems like it'd work quite well. It stops your players from leveling past level 6, which would automatically limit their hit points. Instead, they get feats every 5000xp. This looks like it could replace the limits on player health, and then limiting monster health isn't as broken either since the player characters can't consistently cause, say, 30 damage (if you set the cap at 30 or higher, this would be a quite elegant solution).

Other alternatives

An alternative solution could be to replace HP with a more lethal system instead, or increase potential damage. Making all damage dice explode makes a dagger blow much more threatening, since you could roll several 4's in a row quite easily over the course of a long game. The stress tracks from FATE might also be more suitable, if you can find a good way to port them over. Lastly, consider switching to a system that places more emphasis on danger, such as Harnmaster (known for being both dangerous and simulationist).

tl;dr

You can't cap hit points in D&D 3.5 without seriously breaking the game, and there aren't really any ways to completely fix the problems you cause. Instead, look at capping monster hp and using the E6 system for the players.