Brand new 13" Inspiron 5000 wifi capped at 150mbps (dual band 3165ac)

The 1x1 antenna design is the culprit.  The AC7260 remains a great 2x2 card even today, and the AirPort Extreme card is probably 3x3 since it's 802.11n (it's rare to see 3x3 AC devices other than routers). Extra antennas allows multiple simultaneous data streams, which can significantly increase maximum real-world throughput.

The fact that the 3165 is rated for "up to" 433 Mbps is pretty meaningless in the real world, just like every other WiFi speed quoted in marketing materials.  The AC7260 is rated for 867 Mbps, for example, and clearly you're not getting that level of performance out of it either, although in fairness, the only WiFi ROUTERS that can push that kind of bandwidth in the real world to begin with are very recent 4x4 802.11ac routers (like my ASUS RT-AC88U), and then only when acting as a media bridge to another 4x4 802.11ac router. There aren't any 4x4 AC clients to handle that, so making the most of gigabit Internet still requires a wired connection for now.

Anyhow, if you're comfortable opening up your system, you can see whether there's an extra antenna already in the chassis (its connector would probably have a plastic sleeve around it since that card can't use it), in which case you could buy something like an Intel 8265 for ~$30 (in the US) from Amazon/eBay, which is their latest and greatest 2x2 AC card.  If you only have a single antenna in the chassis, then you may be stuck.  You MIGHT be able to buy another antenna (very cheap) and route it to whichever side of the display doesn't already have one, but that would involve opening the display assembly itself, which is not a supported type of service and therefore no instructions for doing so are included in the system's service manual. There's also an excellent chance that would void your warranty.

Newer is not always better, unfortunately. :(

Just purchased a 13" Inspiron 5000, got it set up, things are going fine. Then I do a speed test on wifi. As background, I have 1gbps broadband with an Ubee cable modem/router that supports AC protocol. I have a 3 year old Lenovo laptop with an Intel DB 7260ac that pulls in 300-400mbps. I also have a 5 year old MacBook Pro with airport extreme b/G/n card that pulls in 250mbps. The new Inspiron only gets 150mbps.

I will be working on this the rest of the day but right now, my XPS 13 with an 8265 is showing 144 Mbps which will jump to 176 Mbps while I am watching it, so ..

How are you measuring your speed?  Have you tried changing the systems location and orientation to the router?

When I try to compare numbers, I keep a close eye on where MBps or Mbps is being referenced.

I have some errands to run this morning but I will be working on this today to see if I can discover anything.  But I agree with what was said about the numbers being overblown when stating capabilities.  I do have a system showing 866.7 Mbps on the adapter status page.

I've been using the various speed tests by ookla, Google fiber, Xfinity, fast.com. they all measure by megabits per second (not megabytes). I run the tests multiple times to average out the results, but it's all very consistent: the Inspiron never goes above 150mbps, the other laptops always do. The laptops are all within 6 feet of the router, no obstructions.

I was CCNA certified over 10 years ago, but am no longer in tech and pretty rusty on new technologies. So, I can understand that my Lenovo has a 2x2 card and has a max speed of 867mbps. Windows states the established speed is 867mbps when looking under the network connection. I can also understand that the MacBook likely had a 2x2 b/G/n card, which is why it can pull a theoretical max of 300'mbps (260mbps actual speed). But from what I gather online, the 3165ac card in the Inspiron with a 433mbps theoretical max with 1x1 should still outperform a b/G/n 2x2.

The laptop is literally one day old, so it's not worthwhile for me to already start buying components and upgrading. Windows reports it established a 433mbps max speed, so it sounds like it is utilizing AC protocol, yet speeds seemed capped at 150mbps. It sounds like a literal cap, meaning it never goes up past 150 and average out. It just hits 150 and stays there.

Interestingly enough, I see the 5Ghz setting only shows "20Mhz" and "Auto", but no 80Mhz setting. Meanwhile my router is set to 80Mhz. Setting both to 20Mhz doesn't fix anything though. It actually makes it slower to 100mbps. Also, when I force the router to use AC only, I actually get worse speed (around 80mbps) on the Inspiron.

My system was on the 2.4 GHz band and increased to 868 Mbps when I changed to the 5GHz.  

Are you sure you are running on the 5GHz radio?  Do you have different SSIDs for each band?

I'm definitely on the 5Ghz band. They are named distinctively. I played around connecting to both bands, but I get only 40mbps or so with 2.4Ghz. Your 8265 is a 2x2 with max speed of 867mbps, so I'm not surprised you get good speed on it. I'm curious if anyone with the 3165 gets better than 150mbps stored, considering its on all the Inspiron series laptops.

I still have the 3165 card which came on my Inspiron so I could test if we can't find another answer.  I do believe you should be able to get a speed over what you seem to be showing.

Are you looking at the Adapter status page or some other speed utility?

We had someone the other day who had a bad connection on the card's antenna.

If the laptop is a day old, WiFi throughput is that important to you, purchasing new components doesn't interest you, and no other solutions avail, you may want to exchange that laptop for a model that includes a 2x2 higher-end AC card like the 8265.  Unfortunately I don't have any experience with the 3165, but just as a data point, on my 8265 I also only have 20 MHz and Auto for channel width options on both 2.4 GHz and 5 GHz, and both are on Auto.  Speaking of channel width, if your router has an Auto or "20/40/80MHz" setting rather than requiring you to pick a specific width, you may want to consider using that instead, because forcing fat channels can actually end up hurting performance overall, depending on the amount of congestion in the airwaves.  This is admittedly more of a problem in the 2.4 GHz band where there are far more devices concentrated in far less available spectrum (which is why some WiFi clients actively refuse to use 40 MHz on 2.4 GHz), but even with 5 GHz it may not always be a net improvement.

Also, while distinctively naming your SSIDs is useful for troubleshooting, for daily operation it's usually better to name them identically, unless you have one of those routers that annoyingly refuses to do this. The simple reason is that identical naming allows the device to choose whichever band will perform better at any given time, and with laptops that roam around the house, at longer distances, 2.4 GHz may actually outperform 5 GHz.  If they're distinctively named, the client will stick to whichever network is higher in its list, even if it's not the optimum choice.