The AI is right that a Peerless Assassin crushes the AMD stock cooler, there is no way it’ll fit. It isn’t even close.
I’m seeing some G509 pictures that don’t even have an exhaust fan. If that’s your model as well, that’s the solution and it’s $10.
Careful not to let compressed air spin the fan blades. It can generate current that your parts may not be particularly happy with.
My understanding is that this applies to all fans.(Case fans, CPU cooler, GPU, PSU, etc…) Corrections welcome if I’m wrong about this.
I took a look at a picture of a Peerless Assassin, and on first impression I did think “no freakin way that will fit my box” but AI begs to differ (I know, AI doesn’t always know what it’s talking about- need to do some measuring I guess).
Otherwise no, my G509 does not have an exhaust fan, so I guess if a better cooler won’t fit, a simple exhaust fan upgrade is my best bet, thanks.
Yes, the Thermalright Peerless Assassin 120 SE (which stands 155 mm tall) will fit inside the PowerSpec G509 case (built on a chassis with a 160 mm CPU clearance limit) alongside your AMD Ryzen 5 5600X****. [1, 2, 3, 4]
Specifications Breakdown
- CPU Cooler Height: The Thermalright Peerless Assassin 120 SE is 155 mm tall.
- Case Clearance: The PowerSpec G509 enclosure (commonly based on a 160 mm limit micro-ATX/mid-tower layout) offers about 160 mm of maximum vertical space from the CPU to the side panel.
- Socket Fit: The cooler natively includes the AM4 mounting brackets required for the Ryzen 5 5600X. [1, 2, 3, 4]
Important Tips for Installation
- RAM Clearance: If your RAM sticks have very tall decorative RGB heatsinks, the front fan of the dual-tower cooler might rest against them. You can slide the front fan slightly higher up on the heatsink fin stack if necessary, but remember that doing so will increase the total height past 155 mm and it might get too close to the glass side panel. [1, 2]
- Airflow: Upgrading from the stock AMD cooler to the Peerless Assassin will significantly drop your 5600X temperatures and reduce fan noise under heavy gaming workloads. [1]
Argh, did not know that! I was spinning the fan pretty good with the air. Didn’t seem to damage anything afterward, though. Will be more careful in future, thanks.
The CPU cooler height limit on a Lian Li 170 (the G509 case) is only 135mm.
Don’t let that stop you though. Once the cooler doesn’t fit, you can justify buying a new case.
Until someone gives a more definitive answer, it is possible that the “don’t spin fans with compressed air” rule only applies to case fans.
Probably better safe than sorry, though.
Yep, looks like you’re right. When I ask AI the specific cooler height for a Lian Li 170, I get this:
The maximum CPU cooler height limit on the Lian Li Lancool 170M computer case is 136 mm (5.35 inches). [1]
Quick Specifications
- Max CPU Heatsink Height: 136 mm
- Motherboard Support: Micro-ATX, Mini-ITX
- Max GPU Length: 270 mm
- Max Power Supply Depth: 160 mm [1, 2, 3]
(Note: If you were actually referring to a Lian Li case that features 170 mm clearance for CPU air coolers—such as the O11 Air Mini or the O11 Dynamic Mini—the cooler height limit for those models is 170 mm.) [1, 2]
Would you like recommendations for low-profile CPU coolers that fit under the 136 mm limit of the Lancool 170M?
Yes, Google Lens, I would like that…
Yes, several highly-rated compact air coolers fit perfectly within the unique 136 mm height restriction of the Lian Li Lancool 170M. Because the case supports micro-ATX and mini-ITX motherboards, choosing a cooler with good RAM and PCIe clearance is essential. [1]
The top low-profile and mini-tower choices available at retailers like Micro Center and Newegg include:
Top Low-Profile (Top-Down) Coolers
Thermalright axp120-x67 RGB Low Profile Air Cooler axp120 x67
- Standout Value: Delivers exceptional cooling per dollar in a slim format, capable of handling higher workloads nearly silently.
- Key Dimensions: Stands exactly 67 mm tall with a 120 mm ARGB PWM fan. [1, 2]
ID-COOLING IS-67-XT Low Profile CPU Cooler
- Compact Design: Uses six high-performance heat pipes and a 15 mm slim fan optimized for tight builds.
- Key Dimensions: 67 mm total height with a broad multi-platform mounting kit. [1]
Noctua NH-L9i-17xx Intel LGA1700 Low Profile CPU Cooler
- SFF Premium: The perfect zero-interference choice for ultra-compact micro-ATX setups where memory clearance is a priority.
- Key Dimensions: Extremely flat 37 mm height utilizing a premium 92 mm fan. [1]
Best Compact Tower Alternative (Under 136mm)
If you prefer a traditional front-to-back tower airflow style instead of a top-down blower, look for a specialized 92 mm mini-tower cooler: [1]
Noctua NH-U9S Premium CPU Cooler with NF-A9 92mm Fan
- Tower Alternative: Offers traditional tower airflow while remaining short enough to fit inside strict case dimensions.
- Key Dimensions: Stands at exactly 125 mm tall, safely below your 136 mm limit. [1, 2]
What specific CPU model (Intel or AMD) are you planning to cool in this build? Knowing the chip will help ensure the cooler can handle its thermal output.
The AMD Ryzen 5 5600X is a highly efficient 65W TDP processor. It generates relatively low heat, meaning any of the compact coolers listed below can easily handle its thermal output without loud fan noise.
The top compatible coolers for your Ryzen 5 5600X in the Lancool 170M case include:
- Thermalright AXP120-X67:
- Best Overall Performance: Features 6 heat pipes and a larger 120mm fan that keeps the 5600X exceptionally cool and quiet.
- Specs: 67mm tall.
- Noctua NH-U9S:
- Best Tower Option: Traditional tower design that directs hot air directly toward the rear case exhaust.
- Specs: 125mm tall with an ultra-reliable 92mm fan.
- ID-COOLING IS-67-XT:
- Budget Pick: Offers similar top-down cooling performance to premium brands at a lower price point.
- Specs: 67mm tall.
- Noctua NH-L9a-AM4:
- Maximum Clearance: An ultra-compact option specifically tailored for AMD sockets that guarantees 100% RAM compatibility.
- Specs: 37mm tall.
It’s potentially also not good for the fan bearings, especially if you let the fan free-spin to rotation rates the bearings weren’t designed for.
When I dust out fans (or the heat exchanger behind them) I restrain the fans so that they don’t spin. That way I can play the airflow over the parts in a controlled fashion, as well as preventing over-rev damage.
Keep in mind that the main issue is the build-up of hot air in your case. These coolers will help by offering more mass to absorb heat and pulling heat faster, but fundamentally hot air isn’t going to cool well. You know that’s the problem because you saw a dramatic improvement once the side panel was removed and used a fan to force air through the case.
If you want to buy a new cooler because it’ll do a better job and be quieter, that’s a nice quality of life improvement (especially compared to an open case.) Make sure you’re solving the underlying problem too. Otherwise you’re not going to get a lot of value out of the purchase and effort to install it.
You mean like getting a new case that has a mesh front panel instead of solid? That’d probably fix it nicely, but would be a massive PITA.
Yeah, you know, the thought has crossed my mind lately “hmm, maybe I should just go buy a brand new top o’ the line gaming computer”. But components are so expensive these days. Not that I can’t afford it, but can I justify it? As a mid-level gamer, I should be ok with mid-level components, as long as they are properly tuned up and cooled down. At least for the near future.
A new case, on the other hand…that might solve a lot of my issues-- give my existing components more room to breathe, and room to grow with better CPU coolers and such… 
If you’re going to get a new case, it makes little sense to transfer your old hardware when you could install new hardware for only several thousand more, right?
2077 is pretty good on medium settings at 60 fps, but it’s a bit better at ultra settings and 144+ fps.
Curse you 
It’s a huge hassle, obviously, having to take apart an entire computer and then building in the new case from scratch.
However, at this point I think you are starting to see the real value in choosing every part yourself versus a pre-built. As a general rule, build your own is more expensive than an equivalent pre-built because you likely choose better parts for yourself. Nicer power supply to keep all your expensive components safe, nicer case with better air flow and more room for coolers and power supplies, faster ram, etc…
The actual performance difference between a build your own with hand selected parts versus a pre-built is probably negligible in terms of FPS, but it will generally run cooler, quieter, and last longer.
Think of how confident you’d be going forward after assembling it yourself. You must have a Microcenter nearby and they have great deals.
I think a few people in this thread assembled their first PC with the advice of other Dopers. Another crucial gaming rite of passage.
Is a PC really your own if you haven’t cut yourself on its sharp protrusions while trying to reach a screw and bled into it?
Actually, wait, this reminds me of a question I had for you, OP. At least I think it was you.
Someone here on the boards built or bought a pre-built several years ago, around the same time as you. At the time, the hard drive came up, and it turned out they were getting a QLC drive. I recommended looking for a TLC drive instead (longer lifespan) but I think it ended up being a pre-built without customization options.
Anyway, if it was a you, I would be curious to compare our “drive life remaining” stats from HWInfo64. My TLC system drive currently says 100% life remaining after 5.5 years. Honestly, that might be more robust than I needed.
If a qlc system drive from 4 years ago is still at like 85% life remaining, that might actually be the smarter buy.
Both my kids decided they had to have custom-built machines as teens. They spec’ed all their own components, but when it came time to the building, they got stuck, and I ended up doing much of the putting together.
So when I decided to buy a new computer 5 years ago, I said, “eh, I’ll just get a decent pre-built” 
Nope, wasn’t me. I don’t even know what type of hard drive initialism I have, other than SSD. How would I check to see if I have a QLC or TLC drive?
@SenorBeef recommended I get HWInfo64 as well. Will likely download this weekend.
Note that if you run HWInfo64 to poll the data, you can also run RivaTuner Statistics Server (RTSS) to display any of the HWInfo64 data you like in an overlay during gameplay. Both are 100% freeware, no ads or anything.
I don’t normally use the overlay, but it’s fantastic for digging into how your computer is running.
Here’s a sample screenshot showing my overlay. You can place it anywhere on screen, change the color, etc… I have it showing utilization %, temperature and fan speeds for the CPU and GPU, then I added the ram info and system/case fans and finally the FPS, which RTSS seems to really want to put on its own line. As may be clear, I set up this overlay while setting up my fan curves.
Also, I think you said you installed Afterburner. Afterburner is the only way I could manage to set my gpu’s fan curves, which are not controlled by the motherboard.
Minor update: I changed my CPU mode from ‘eco’ back to ‘default’, cracked open the side panel, turned on the external fan, and did a test with a couple battles in CP2077 (the NCPD scanner ‘crime in progress’ sites are good for finding quick, intensive battles to test with).
It resulted in significantly better performance. Still a couple minor stutters, but nothing too bad, and hopefully even those can be resolved with the BIOS tweaks / tuneups suggested in @Whack-a-Mole ’s post upthread.
The CPU also didn’t heat up to any concerning degree- a couple short spikes in the low to mid 80s, but a lot of time in the 70s.
Well that’s a good news / bad news situation. The good news is that it sounds like all you need is a new case, which in the grand scheme of things is dirt cheap compared to a GPU or RAM. The bad news is that “a new case” is the most labor-intensive fix possible when it comes to computer hardware. (And how infuriating if it didn’t fully fix the problem.)
This is mostly a cyberpunk thing, right? That game is super demanding from what I understand. You never noticed any issue with “lighter” games like fallout 4, right?
Are there any other demanding games you have your eye on? (Basically any big studio game from the last few years.) That Indiana Jones game comes to mind as one with ridiculous requirements.
If it’s only a problem for cyberpunk because you aren’t particularly interested in other AAA games, how many hours do you envision playing? Maybe just take the side panel off and call it good enough for cyberpunk, then put it back on when you finish the game. That would certainly be the easiest and cheapest solution. There is no harm running your computer without the side panel other than a little extra dust accumulation.
RE: A new case…
The important thing to remember is all the heat sinks in the world, no matter how good, need to exhaust that hot air out of the case. This is why intake fans are so important (and usually one exhaust fan for the CPU…but you can exhaust out of the top through a radiator…lots of ways to go about it).
In general, you want a positive pressure case. Enough air is coming in that all the exhaust vents are pushing air out. Need not be a lot…indeed a barely perceptible breeze where there is no fan is sufficient. Also, keeps dust out (assuming your fans push air through some kind of filter…be sure to clean those every month or two or whatever works for you).
This is why you often see three big fans up front or on the side and sometimes on the bottom.
I would encourage you to buy “good” fans and not the cheapest ones. The main thing you want is silent fans. In my early days of PC building my PC sounded like a plane running its engines. Today I have 10 fans in my PC and unless I turn them up to near 100% I can’t hear them at all no matter what my PC is doing. For that I use expensive fans and pretty sure I can go cheaper and still do as well but it was also an aesthetic thing.
Fans are one of those things that seem almost an afterthought like a power supply that turn out to be worth more consideration.
Whether you can fix your current case with a new fan/heat sink set or just need a new case I do not know. I’d first check to see if you can solve the airflow problems in your current case. If you buy new fans for the current case and they don’t work well you can just take them out and put them in a new case. Nothing lost (probably).
ETA: The bigger the fan the more quiet it is in general. High RPMs are where the noise comes from (and bad/cheap blade design). A bigger fan can push the same volume of air as a smaller one but at lower RPM. The case manufacturer will have a spec sheet on what size fans can fit where. Be sure to check it when planning your fan setup.