So, I have a power gamer in one of my games. He rarely role plays, and he is always looking for gold to get weapons and horses, even though he doesn't need it. He is also somewhat of a min maxer which I don't really have a problem with, but he goes for power over role play. Whenever I try to talk with him about it, he denies it. How would you deal with him?

You can't really force someone to role play. 

Also, we don't have alot to work with here. Its basically "I say that this player is a powergamer. He says he is not" The only thing we have to go off of is that he wants to try and get alot of gold, which isn't that unusual for an adventuring party. 

If you want to try to curtail his dependence on finding gold, you could run an adventure set in a place where resources would be scarce (like a desert)

OR where things like gold are heavily guarded and trying to acquire it would put the character (or the party as a whole) at risk (like a dragon's hoarde or a well-guarded bank). In this second example, you are giving the player the opportunity to get what they want, but making it clear that it will not be easy. Perhaps, to encourage role play, put in a few social encounters that could make the "heist" a bit easier

It sounds like that's what he wants to do, I wouldn't fight him on it. Maybe try tailoring some challenges more towards optimization so that some of the tricks the power gamer has up their sleeves that they're probably itching to use can come into play. Maybe put an obstacle course in the player's way so they can finally use their 10 ft pole to check for traps and let them shine. Maybe an enemy tries to escape on horseback and the power gamer can have a quick, fun chase scene so they can get some use out of the horse. 

You don't have to change the whole game to cater towards this player, but, knowing what you do about what they find enjoyable in the game, it would be a shame not to include something for them every now and again. 

Also, re; gold. Maybe come up with more things to spend it on. It's a natural impulse for players to want to amass a lot of gold, 5e is just fairly bad at giving players things to spend it on. It's a little extra work on your part, but maybe you could give them an opportunity to buy a home or a manor, somewhere they can use as a home base and tick out as they see fit. Maybe a ship, if ship travel is prominent in your game. Maybe a pet or something. 

Here's my question... is he interrupting role play with his insistence on gold hunting and battling? If not... maybe he's just happy to observe during the roleplay moments. Some people are like that... they l like being there and observing what's going on, but don't always feel comfortable getting involved. Roleplaying can be uncomfortable or embarrassing for some people.

Alternatively, if he's not paying attention and is just staring at his phone when you're not fighting then it would be best to discuss that specifically. Although I do think it would be fun to lean into that with his character... like any time he's not paying attention narrate it as his character kind of just staring off in the distance or getting distracted by something silly.

However, if he's constantly heckling the other players or trying to cut roleplay short maybe he's just not a good fit for your table. There's nothing wrong with being more of a wargamer than a roleplayer, but it's hard for someone who really wants to play one type of game to be at a table where everyone else wants to play the other way.

Greed

You corrupt the heart of your enemy, giving them a crippling weakness for wealth of all kinds. Choose a humanoid you can see within range. Casting this spell requires you to show the target a gold or platinum coin in your hand and say the incantation. The target must then make a Wisdom saving throw. On a failure, it must make the saving throw again at the end of each of its turns. If it successfully saves against this spell three times, the spell ends. If it fails its saves three times, it gains the following flaw: "I hoard wealth like a miser, and I will do anything that will grant me more money or power, including betraying my friends." The successes and failures don't need to be consecutive; keep track of both until the target collects three of a kind.
The spell can be dispelled only by a dispel magic or remove curse spell cast at 9th level, or a wish spell.

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You see this spell? Cast it on him, and make a situation where he betrays the other characters in his quest for gold. If the greed is affecting the gameplay and fun for everyone you should not put up with it in game.

The character is spoiling your fun.  How about the other players?  If not, let them have all the gold they can carry.  It's not like there's much they can spend it on.  Maintaining a Lifestyle is only expensive for an Aristocrat, and what the heck?  Why not?  If the others are into roleplay, the intrigue that happens around members of the Aristocracy ought to keep them at least the other players entertained.

If nobody is having fun, then try to talk it all out with everyone, if that doesn't work take it private, and if that doesn't work, give them the option of leaving your game or changing their play style.

Something that I do that helps with min-maxers is limit which sources I use in my campaigns or one shots. I give my players a list of which sourcebooks I’m using in a campaign, which optional rules they can use when building characters, and have them use the point buy system for their stats. It limits the worst of the min-maxing but it doesn’t eliminate it so the players who love that play style still get to do some of what they love. 

Quote from ARCANE285 >>

He rarely role plays, and he is always looking for gold to get weapons and horses, even though he doesn't need it. 

 I hate to break it to you, but this sounds like roleplaying to me. If he doesn't need it, he could be looking for that stuff because that's what his character wants to do.

Sometimes characters want power. Sometimes characters want to fight. Just because you suspect it's what the player wants doesn't preclude it from being roleplay.

I can get it if the guy is just not engaging with the world at all, but when he does this stuff take a second and consider if he could be possibly speaking for his character rather than just for himself.

I don't really see this as a problem unless he's being really distracting at the table and upsetting the other players. I would probably encourage this player to roleplay more by asking about character motivations, and asking him to describe in more detail what he's doing and/or why his character is doing it. You can also find ways to give and take rewards away. Maybe a thief steals the bag of holding which prompts a quest to retrieve it. Maybe a magically sealed area requires a certain gift of a magical item to open. This forces the player to improvise more and allows you as the DM to give out different magical items without the party (especially the power gamer) becoming over powered. 

If his behavior is ruining the game for yourself and/or the other players, remind them that you have the right to boot them from the table. If not, then let it be. If they’re a close friend, try to work it out. If they’re not and they’re being a jerk by gushing about gold and their build on other player’s turns and role play moments, then you can kick them. It’s all a matter of context and enjoyment.

My advice? TALK TO EVERYONE. If this player is ruining the game and they refuse to change their behavior, kick them from the table. BUT, this should be a last resort. Try to find another solution.

Not trying to dog-pile the responses, but...

I don't see anything in your post that describes a power gamer or a min-maxer. Is the player just being a murderhobo or perhaps using the "that's what my character would do" defense? Are they making the game unfun for the other players? Perhaps they are trying to engage in PvP with the other PCs at the table? You've stated that there has been conversation between you about your concerns, what is the PCs goal? Do they have any flaws, bonds or ideals? Are they driven my money? Is their character loyal to the biggest payout? 

There's a reason the player is doing what they are doing. Their denial of your accusation isn't perhaps incorrect. I'm merely suggesting that maybe an actual two sided conversation be had, one where they give you the premise behind their character and what makes them tick. This will tell you the "why are they doing this thing" and give you the opportunity to include what interests the character into your game. You know, give the player an opportunity to role play what they are interested in.

It sounds like he is simply playing D&D............ The whole point is to slay monsters and rake in gold..........

Troll thread??

Like the others have said, we might need more details.  Because it sounds like he is just roleplaying in a different way.  If he is buying horses and equipment he doesn't need, he's thinking about the character's future.  It really depends on how disruptive this is to the rest of the table. 

I have a player in my current game that didn't give me a backstory, and wasn't interested in doing a solo 'session 0' like I did for the other players. He just showed up on game night. During social scenes he didn't have much to say.  I asked him once if he wanted to work out more of a background, because I was afraid he didn't feel as included since I couldn't tie his character in more directly.  He said something like "Nah, I'm happy.  My character is ready to go wherever the party needs him. He doesn't need a reason. He just wants to see the world and help people."

Turns out, he was completely content just to have his character feed his pets and cook while everyone else discussed their next course of action.  He just wanted to play with us, roll some dice, and chill.  He made a character that didn't need a big reason to adventure.  That's pretty great.

If your other players are upset with things they do, that's an issue.  If they are buying horses because they want to use some ridiculous power trick they saw in a video, that could be a problem if it doesn't fit your theme or unbalances the game. Is everyone having fun? Is his behavior disruptive to the table? Is it making it hard for you to run the game? Maybe there is more to the story.

Or maybe he just likes horses.

It sounds like you have made an expectation of how the players will play, and perhaps did not lay this out in a session 0. There's nothing wrong with a character wanting to get gold for horses and weapons - perhaps the yhave a really awesome combo they want to build that requires being mounted with a lance?

Power gaming in itself is not too bad - is the character significantly more powerful than the other player's characters, or are they "acting powergamey", in that they are interesting i ntheir characters power and progression more than the progression of the story?

The first is an issue of balance, and you will need to work out their weaknesses or build encounters (including puzzles, traps, and social) which need multiple players to be in different places at the same time to succeed. Including multiple events which need teamwork will balance out a powerful character nicely, without making the game about them.

The second is about how they play their games, and it is worth emphasising that if they are enjoying it, and everyone else is enjoying it, then it's not a problem. So 3/4 of the party are interested in the lore you've created and the mystery of wh okeeps releasing giant crabs in the city, and one of them is just interested in getting rich and buying cool stuff. That's absolutely fine - and is roleplay. Han Solo is only in it for the money - at first. Not everyone does heroing for the sake of being a hero, and that's how you get a good dynamic in a group!

So to reiterate what others have said - we need to know more to be able to help!