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Case flow dynamics

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April 15, 2011 10:07:37 AM

One thing i feel needs to be talked about more when building a PC is how air should flow in a system. It is not 100% clear to me how things should flow, although i have an idea.

The case in question is an antec 300 illusion, the power supply is a raidmax http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Ill assume you all know the antec 300.

Ok, so the two front fans are intakes and the top 140 and back 120 are exhausts. Now, the antec does not have a perforation on the bottom where the PSU mounts, so that means i need to have the fan upwards drawing inside case air and shooting it out the back correct?

If this all sounds right, would it make sense to install a side fan (as an intake) to help the PSU draw in cool air rather than the hot air provided by the GPU.

I just think manufacturers should include this kind of stuff with their products, case and PSU manufacturers especially.

More about : case flow dynamics

April 15, 2011 10:13:38 AM

Sorry, one other thing. I am going to be using a CM 212 plus on an asrock P67 board. Would it make sense to use the fan that comes with the cooler to push air through the heatsink (on the ram side of the motherboard) and rely on the 120mm case fan the exhaust that air?

They seem to line up fairly well.
April 15, 2011 10:14:37 AM

Whenever Possible, the PSU should be taking in air from the bottom of the case (in bottom mounted psu situations) where there should be a vent or mesh, so that the psu is not taking in warm air from inside the PC.
On PC's, Front, Bottom and Side fans are intake, while Back and rear are exhaust.
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April 15, 2011 10:15:26 AM

Also, the psu should have about 1.5 - 2 cm from the bottom of the case.
April 15, 2011 10:17:13 AM

Flightsimluke said:
Whenever Possible, the PSU should be taking in air from the bottom of the case (in bottom mounted psu situations) where there should be a vent or mesh, so that the psu is not taking in warm air from inside the PC.
On PC's, Front, Bottom and Side fans are intake, while Back and rear are exhaust.



Right, i kind of figured the PSU fan should intake the air from the bottom of the case in most scenarios except that my case (and have seen many others) simply do not support this. Meaning there is no mesh and its just solid metal. I would also prefer it to have a washable filter in this situation as well.

Anyone else want to take a crack at this?
April 15, 2011 10:18:55 AM

Well, if your psu has a screwed on fan protector, unscrew it and fit a filter? And yeah, get a side fan.
April 15, 2011 10:25:29 AM

Flightsimluke said:
Well, if your psu has a screwed on fan protector, unscrew it and fit a filter? And yeah, get a side fan.


See, this is exactly what i am talking about when i made this thread. In no situation should i need to modify components that should be 100% compatible.

It just boggles my mind that pointing the PSU up or down is even an option from case to case. Airflow is one of the MAJOR selling points because cooler systems run better, but hardly anything is ever talked about things like my post here is.

I see it two ways here:

1. Point it upwards and decrease the lifetime of my PSU and possibly lower GPU temps (probably the best option considering the price difference between these two components).

2. Point it downwards, forcing me to go to the store and design some sort of filter, as well as cutting a large hole in the bottom of the case. Trust me, if i did not do these two things i would be in a worse off situation than just pointing the fan up and sucking in case air.
a c 273 ) Power supply
April 15, 2011 10:34:22 AM

The Antec 300 is fine no problems there.
I have my Corsair HX750 mounted fan down in my Antec 902 no mesh cut-out.
You have a Raidmax and i strongly recommend you mount it fan side up.
Imo side fans do little other then adding more dust.
Your case has excellent airflow.
I would have aimed a little higher then a Raidmax psu though.
April 15, 2011 10:38:06 AM

davcon said:
The Antec 300 is fine no problems there.
I have my Corsair HX750 mounted fan down in my Antec 902 no mesh cut-out.
You have a Raidmax and i strongly recommend you mount it fan side up.
Imo side fans do little other then adding more dust.
Your case has excellent airflow.
I would have aimed a little higher then a Raidmax psu though.


I appreciate the reply but where are you getting the "fine" from? There is hardly any room between the bottom of the case and the PSU. Secondly, why "strongly recommend" pointing it up just based on the fact it is a raidmax?

Also, this is by far the cheapest modular PSU on newegg and it has great reviews. It is nearly 80 plus certified as well. (those ratings are highly overrated anyways).
April 15, 2011 10:47:33 AM

You could put another fan on your CPU heatsink and set it up push-pull so the air is taken in from the RAM side and then vented out into the rear exhaust.

Side fans can actually make airflow worse. They have applications for cooling graphics cards, but generally air should be 'smoothly' coming in the front and bottom, heating up and rising to be vented out the top and back. Intaking air at 90 degrees to this from the side can introduce some interesting flow situations which may impact case air flow and cooling.
April 15, 2011 10:52:07 AM

diellur said:
You could put another fan on your CPU heatsink and set it up push-pull so the air is taken in from the RAM side and then vented out into the rear exhaust.

Side fans can actually make airflow worse. They have applications for cooling graphics cards, but generally air should be 'smoothly' coming in the front and bottom, heating up and rising to be vented out the top and back. Intaking air at 90 degrees to this from the side can introduce some interesting flow situations which may impact case air flow and cooling.


Thanks for the reply diellur. When i was talking about the CPU cooler i meant that i would use the included fan as a "push" and the 120mm case fan as the "pull". I was wondering if this was standard practice on the 300 cases being that the case fan aligns so nice with the heatsink.

I do agree with the side fan part and airflow, but i was just thinking of solutions so the PSU could suck in cooler air. But possibly the front fans will provide enough air with the PSU fan facing upwards.

I think i might just spray paint some cardboard black and cover up the side vent (i am a smoker, this way the only intake is the front panel which has a washable air filter).
a c 273 ) Power supply
April 15, 2011 11:08:30 AM

Scotty99 said:
I appreciate the reply but where are you getting the "fine" from? There is hardly any room between the bottom of the case and the PSU. Secondly, why "strongly recommend" pointing it up just based on the fact it is a raidmax?

Also, this is by far the cheapest modular PSU on newegg and it has great reviews. It is nearly 80 plus certified as well. (those ratings are highly overrated anyways).

The Antec 300 is a highly regarded and reviewed case.Just because it doesn't have a bottom psu cut-out doesn't make it less of a case.
I've owned one and currently have a 902 which lacks the same feature.
I have a CM690II which has a bottom psu cut-out and it's poorly implemented.The psu has to be removed to clean the filter.
The filter and psu fan are in constant need of cleaning.
Trust me you aren't missing anything.
And i would mount it side fan up simply because of all the unknown factors regarding your psu.
It's not hard to get a psu to pass ECOS 80+ certification.
It suggests to me the psu is an old inefficient design that runs on the hot side and may or may not actually deliver its labelled power output.
As far as reviews go i don't consider Newegg user reports a review.
a b ) Power supply
April 15, 2011 11:11:36 AM

^+1

I've never known a Raidmax PSU to be highly regarded or recommended on any tech website/forum. As you say, "this is by far the cheapest modular PSU on newegg"
April 15, 2011 11:18:53 AM

davcon said:
The Antec 300 is a highly regarded and reviewed case.Just because it doesn't have a bottom psu cut-out doesn't make it less of a case.
I've owned one and currently have a 902 which lacks the same feature.
I have a CM690II which has a bottom psu cut-out and it's poorly implemented.The psu has to be removed to clean the filter.
The filter and psu fan are in constant need of cleaning.
Trust me you aren't missing anything.
And i would mount it side fan up simply because of all the unknown factors regarding your psu.
It's not hard to get a psu to pass ECOS 80+ certification.
It suggests to me the psu is an old inefficient design that runs on the hot side and may or may not actually deliver its labelled power output.
As far as reviews go i don't consider Newegg user reports a review.


I never said i didn't like the case, in fact i think it is the best 50 dollar case ever produced. I am merely saying it is a shame they did not include support for bottom mounted PSU and include a mesh grille and a filter.

Your reasoning for pointing my raidmax up is still unclear, even though that is now how i have decided to mount it. "Unknown factors"?

Sure i would like to have a 80+ gold or silver rated PSU, but for my budget this PSU fits the bill. It is bordering on being 80 plus certified but i am guessing just missed the mark (says 80% efficiency in the specs). But the kicker on this PSU is that it is a modular design for 40 bucks. Nothing on newegg comes even close to delivering that kind of value. I looked at some 120 dollar antec's that claimed they were modular, but they actually had more cables hard wired than this raidmax does (and cables i do not need, just more cables to try and hide in the case).
April 15, 2011 11:27:11 AM

mi1ez said:
^+1

I've never known a Raidmax PSU to be highly regarded or recommended on any tech website/forum. As you say, "this is by far the cheapest modular PSU on newegg"




In 15+ years of building my own PC's have i ever had a PSU unit fail on me, the most recognizable "brand" name is my current 350 watt rosewill that has not missed a beat in 6 years.

I understand why 80+ certification is a good thing (While power savings is always good, the main benefit is less wattage lost as heat, and we all want cooler systems, but most current PSU are all nearing and very close to 80+ certification some manufacturers have even "cheated" the system and got caught later, i could link the same model but 730 watt raidmax and it is 80+ certified that tells me the 530 just barely missed the rating the day they were tested), and i definitely wanted one but there is simply no denying the value of this modular raidmax PSU.

When talking about budgets, everything has to be considered. The next step up would a 550w antec that is not 80+ rated either, and as i stated in above post actually is not AS modular as this raidmax model meaning more un-needed clutter in my case. I believe that PSU is 80 dollars shipped, double the price of this one.
a c 273 ) Power supply
April 15, 2011 11:41:59 AM

Well you certainly asked me why or how i considered the 300 fine!
Raidmax isn't known for high quality psu's.
Buying a psu based on price alone isn't exactly a good idea.
The psu is the last area of your build where you would want to pinch pennies.
Units backed up with reliable test reviews is far better.
I don't see one anywhere on the web for your model.
That's why i question it and give it an unknown factor.
I'll leave it at that and wish you the best of luck with your build:) 
April 15, 2011 11:46:45 AM

Scotty99 said:
I think i might just spray paint some cardboard black and cover up the side vent (i am a smoker, this way the only intake is the front panel which has a washable air filter).


Not sure if you're aware, but you can buy filters off of eBay which are perfect for side panel fans. I've got one on my server...no fan there, but the filter catches any dust that may try and enter the system. Just might save you the bother with the cardboard.
a c 91 ) Power supply
April 15, 2011 11:48:32 AM

Which video card(s) are you going to use..? Also, give details on the exact processor model and the amount of overclocking (if any) you plan to get on your CPU.. As for the PSU, I hope you do realize that it won't -

1. Deliver the advertised wattage (check out the 12V rails).

2. Maintain the same efficiency across all load peaks (its rated as upto 80% efficient which means its efficiency is lower than that).

3. PSU's from good brands are sure to deliver their rated efficiency at temps upto 50 degree celcius. Nothing as such mentioned with this PSU. And in this case wherein the PSU will be drawing in hot air from inside the case, you would want it to be rated to deliver at the highest temps.
April 15, 2011 12:15:45 PM

Emperus said:
Which video card(s) are you going to use..? Also, give details on the exact processor model and the amount of overclocking (if any) you plan to get on your CPU.. As for the PSU, I hope you do realize that it won't -

1. Deliver the advertised wattage (check out the 12V rails).

2. Maintain the same efficiency across all load peaks (its rated as upto 80% efficient which means its efficiency is lower than that).

3. PSU's from good brands are sure to deliver their rated efficiency at temps upto 50 degree celcius. Nothing as such mentioned with this PSU. And in this case wherein the PSU will be drawing in hot air from inside the case, you would want it to be rated to deliver at the highest temps.



First thanks to the guy who mentioned the filters from ebay, if microcenter has nothing like this ill check out ebay.


And @ quoted guy:
1. Video card http://www.newegg.com/Product/Product.aspx?Item=N82E168...
2. Processor http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I will probably do a mild overclock of 4.0ghz and see if that fits my needs.

Side note, what do you think of the deal on that video card eh? It is a brand new model from sapphire and it is very impressive for the price point.

And i do realize how they test for 80+ certifications at different temps, but i am really sick of the debate atm. This thread is about airflow and not PSU manufacturers:p  I am going to be running a single card and i have no doubt it will supply the power to the card at all temps. Bottom line is that it is a true modular PS that is 40 bucks. Contrary to popular belief i do think a PSU is actually one of the places you can skimp a bit when building a new rig (has worked for me in the past). Hey, you gotta skimp somewhere on a budget.
April 15, 2011 12:18:59 PM

Scotty99 said:
First thanks to the guy who mentioned the filters from ebay, if microcenter has nothing like this ill check out ebay.


You're welcome - link below to what's currently around:


April 15, 2011 12:24:21 PM

diellur said:
You're welcome - link below to what's currently around:




Is this the UK boards? lol

American BTW. Not sure how this happened, i just navigated from THG main page and clicked forums at the top heh, oh well it all works!
April 15, 2011 12:25:39 PM

Scotty99 said:
Is this the UK boards? lol

American BTW. Not sure how this happened, i just navigated from THG main page and clicked forums at the top heh, oh well it all works!


Ah, yes...I'm in Scotland! Still, gives you an idea of what you're looking for. I imagine they're just as common over the pond as they are here.
April 15, 2011 12:31:16 PM

diellur said:
Ah, yes...I'm in Scotland! Still, gives you an idea of what you're looking for. I imagine they're just as common over the pond as they are here.



I actually think i am on the wrong forum board somehow O.o

Because when people reply i get an E-mail and it says "Tom's hardware UK and Ireland forums".
April 15, 2011 12:32:46 PM

Scotty99 said:
I actually think i am on the wrong forum board somehow O.o

Because when people reply i get an E-mail and it says "Tom's hardware UK and Ireland forums".


That's where the best people are. ;) 
April 15, 2011 12:34:59 PM

diellur said:
That's where the best people are. ;) 


I am all of a sudden craving fish and chips...
a c 91 ) Power supply
April 15, 2011 5:22:33 PM

Hey that is a good deal for a nice video card.. So well done on that.. As for your PSU theory (yeah I know here we go again), it is the most critical component in a PC.. So skimping (in quality terms) is not at all recommended.. Your call though.. All the best..
April 16, 2011 9:17:24 AM

Scotty99 said:
See, this is exactly what i am talking about when i made this thread. In no situation should i need to modify components that should be 100% compatible.

It just boggles my mind that pointing the PSU up or down is even an option from case to case. Airflow is one of the MAJOR selling points because cooler systems run better, but hardly anything is ever talked about things like my post here is.

I see it two ways here:

1. Point it upwards and decrease the lifetime of my PSU and possibly lower GPU temps (probably the best option considering the price difference between these two components).

2. Point it downwards, forcing me to go to the store and design some sort of filter, as well as cutting a large hole in the bottom of the case. Trust me, if i did not do these two things i would be in a worse off situation than just pointing the fan up and sucking in case air.

So... Why ask a question on a forum if you seem to know exactly what you are doing, and will not change your perspective?
a c 144 ) Power supply
April 16, 2011 12:31:46 PM

scotty,
I have 3 Antec 900 cases. I orient the PSU's with the fan up. It gets most of its cooling air from the air that cools the hard drives in the lowest drive bay. PSU exhaust air is about 3 C over ambient. If that truly bothers you, it is just a few minutes' work to cut a hole in the bottom of the 300 or 900 case.

Case modding is no big deal:
Antec 900 case mods for cable management:
http://www.tomshardware.com/forum/264112-28-antec

Side fans - if you have a case with a hole for a side fan, try the case with and without the fan. Use what ever gives you the better temps.

Inexpensive power supplies - You have the cheap junk. Next step up are the things like Raidmaxes and Coolmaxes. They are generally useful in simple, low spec systems. I have used them in budget builds for other people. Generally, they are not too bad if you derate them by 20%. If the box says it is a 500 watt PSU, mentally treat it like a 350 - 400 watt PSU.
!