A little test: Removing PCI slot covers DOES make your GPU cooler... (pic heavy)

ebhsimon · Jan 21, 2014

If you have positive case pressure, with a non reference cooler.
Here's my setup in my Fractal Design Arc Midi R2.
I have positive pressure front to back airflow going on.

I removed the PCI slot covers.

Back exhaust fan:

Top exhaust fan:

Top intake fan:

Temperatures where the PCI slot covers used to be (I measured the temperature of the DVI cable and one of the PCI horizontal pillars, not the actual GPU itself) - and they're hotter than the exhaust fans which means that instead of mixing fresh cool air with warmer GPU air and then exhausting it out the top and back, the GPU air is being pushed straight out the back of the case. Excellent

I can feel hot air blowing out of these open slots, which is a good thing.
Previously I ran Kombustor for 1 hour and got to a temperature of 80C while my intake temperature was 22.1C giving a delta of 57.9C for the GPU.
Then I ran Kombustor for 1 hour again but this time with the slot covers removed. Intake temperature of 24C and GPU temperature of 75C giving a delta of 51C.
That's a difference of 6.9C.

Since I have positive pressure I'm not going to worry about dust flying in, but I do hope that insects don't get in.

Just a little semi scientific test for you guys to try out on your own systems.

PS: I didn't think to record CPU temperatures (doh!), but I don't have another free 2 hours so I'll do it some time in the far future.

REAPER XD · Jan 21, 2014

Nice! Will have to keep this in mind and drill a few holes in my slots.

Great work! REP+1 for creativity haha

ebhsimon · Jan 21, 2014

Thanks. I think it would probably work for negative case pressure too, but who does that..
If I had a vent on the side panel for a fan I probably wouldn't have had to do this.
I'm sure it works because there's an opening for the hot air from the gpu to be pushed straight out before it even reaches the exhaust fan above it due to the nature of positive case pressure.
It reduces the amount of stagnant or non-moving air in the case by allowing a lot of it to easily flow out, and it just so happens to be above and below the GPU which is great because it pushes the hotter air from the GPU out.

I wonder what would happen to the airflow inside the case if I were to add an additional intake on the bottom of the case. It might mess up the straightforward airflow and cause a little turbulence so I'll leave that experiment for later.

Deni · Jan 21, 2014

You may also cut the rear fan grill and it will improve the airflow further. The top grill also looks pretty restrictive but you'd have to cover it with something (maybe dust filters).

ebhsimon · Jan 21, 2014

The top grill used to have a foam filter, which while worked really well as a filter was atrocious for air flow. I promptly removed that. Now it's just a grille which probably does restrict air flow. But I mean I can't go hacking my case up now, I've got to have it looking at least a little decent

EDIT: I prefer not to have any permanent changes to the case, because right now all I've done is just simply removed the slot covers, which most people can do for their cases too.

Deni · Jan 21, 2014

Don't forget that positive airflow doesn't necessarily mean less dust. Without filters on the intakes IMO means more dust inside the case (you're pushing dust inside the case rather than sucking it with negative airflow).

ebhsimon · Jan 21, 2014

I'm completely okay with having more dust flow through the case. I'm going to buy a Datavac 500 soon so I'll have a lot of fun cleaning out my computer every 2 months or so

seross69 · Jan 21, 2014

You would have a lot better temps if you did not have positive or negative pressure. actually even pressure is best you want to move as much air out of the case as is going in...

for every 120 that is intake you should have 120 exhaust. maybe 1 extra intake to account for the GPU fans.

you want air flow through the case to remove the heat and positive or negative pressure will actually restrict the air flow...

ebhsimon · Jan 21, 2014

I have 2 140mm exhaust and 3 140mm intake.
I guess I can add one more fan, but I feel the temperatures now are quite acceptable for the noise produced.

With this layout I imagine the 3 intakes are enough for the 2 exhausts and for the open expansion slots. When I get another fan I'll try use even pressure, but I'm not sure when I'll have another fan.

adre · Jan 21, 2014

Thanks a lot for the info. I am having heat issues with my 7870 XT and this will help

VindalooJim · Jan 21, 2014

Nice post OP.
The DataVac 500 really kicks ass. I've removed the PCI slot covers on my CM 690 II Advanced and while I haven't been able to test it as scientifically as you have, I'm sure it's made some sort of improvement. I've got two ref cards which exhaust most of their heat out the back anyway but a small ammount of it gets exhausted out of the sides close to the back of the GPU near the PCI slot covers- I'm sure that removing them has helped the hot air being exhausted out the sides of the GPU escape the case.

I have positive air pressure: x1 140mm front intake, x2 120mm bottom intakes, x1 140mm on HDD cage blowing onto the GPUs (surprisingly it doesn't seem to do a great deal)
x1 140mm top exhaust, x1 120mm rear exhaust

140mms are NF-P14 FLX
120mms are NF-S12B

EDIT: Cable management is extremely tidy and I have removed all dust filters (intake and exhaust) apart from the PSU's dust filter.

ebhsimon · Jan 21, 2014

Thanks,
I've only heard good things about the datavac, seems I can't go wrong with it.
Also I'm not sure how effective this'd be for reference coolers since they exhaust all the hot air out the back anyway.
I don't have tidy cable management... I mean it's tidy and looks super clean from the front but when you look behind the motherboard it's a giant mess.

doyll · Jan 21, 2014

Quote:

Originally Posted by seross69

You would have a lot better temps if you did not have positive or negative pressure. actually even pressure is best you want to move as much air out of the case as is going in...

for every 120 that is intake you should have 120 exhaust. maybe 1 extra intake to account for the GPU fans.

you want air flow through the case to remove the heat and positive or negative pressure will actually restrict the air flow...

I disagree.
Regardless of how many intake or exhaust the pressure difference between outside and inside of case is almost nothing.. What air goes in comes out / what goes out comes in.
The intake vents are far more restrictive than exhaust vents. Add to that there are many small "vent" in most newer cases like slotted PCI slot covers, venting beside PCI slots, etc. makes it easy for air to escape with more intake fans than exhaust...

What is even more important is how the air flows thru the inside of case... how well the heated cooler / GPU exhaust air leave case without mixing with the cool case intake air we want going to components.

My sig system has no exhaust fans. Only 3x 140mm intakes on PWM control from CPU fan header. Case air temp is a maximum of 2-3c above room temp.

TiezZ BE · Jan 21, 2014

^This

I've done some testing when I changed the case of my current rig (same components). Doyll gave me the ~same info and it's good info!

It is very good to have a positive pressure (more intakes) inside the case when the ventilation holes are in the back. The extra air that is coming in gets pushed out in the back at the vents and that is mainly hot/heated air from the gpu(s).

For those who are looking for more info on this matter: http://www.silverstonetek.com/techtalk_cont.php?tid=wh_positive&area=en

@OP: Nice thread, thx for the effort!

The only things that is 'weird' to me is your intake in the top, it's just next to your output fan in the top. Is there a reason why that one isn't placed in the bottom??

FastMHz · Jan 21, 2014

Maybe one of these slot ventilator fans would enhance the benefit further

francisw19 · Jan 21, 2014

Interesting results, thanks for posting!

I can't tell from the pics, but your GPU is a Twin Frozr type, not reference blower?

ebhsimon · Jan 21, 2014

Thanks to all for the kind words.
Quote:

Originally Posted by FastMHz

Maybe one of these slot ventilator fans would enhance the benefit further

Looks interesting, I might get one just to play around with but I probably won't use it daily since most reviews say it is quite loud. But that's probably because I turn off case fans in pursuit of silence.

@Tiezz be the intake at the top is for the CPU.

@francisw19good eye you have there, it's the 7970 msi twin frozr 3 (excessive coil whine edition)

miklkit · Jan 21, 2014

I had a top fan setup like that for some time, with the front being intake and the rear exhaust. Then the bearings dried up and froze on the exhaust fan and temps went down a bit.

So now it has 4-120mm intakes and no exhaust fans, all behind filters. I still have to clean them weekly too.

The pci slot covers are removed and I can feel the air flow coming out of them and the MSI R9 280X with a small OC has never gone over 67C.

You might consider the Silverstone magnetic filters. They have a 240 version that looks ok.

doyll · Jan 21, 2014

I'm using Silverstone magnetic filter and have for several years. DEMCifiex make magnetic filters too but are much more expensive.
http://www.demcifilter.com/c205/Triple-Fans.aspx

seross69 · Jan 21, 2014

Quote:

Originally Posted by doyll

I disagree.
Regardless of how many intake or exhaust the pressure difference between outside and inside of case is almost nothing.. What air goes in comes out / what goes out comes in.
The intake vents are far more restrictive than exhaust vents. Add to that there are many small "vent" in most newer cases like slotted PCI slot covers, venting beside PCI slots, etc. makes it easy for air to escape with more intake fans than exhaust...

What is even more important is how the air flows thru the inside of case... how well the heated cooler / GPU exhaust air leave case without mixing with the cool case intake air we want going to components.

My sig system has no exhaust fans. Only 3x 140mm intakes on PWM control from CPU fan header. Case air temp is a maximum of 2-3c above room temp.

I wiil not disagree with you and should have explained my self better. but as long as you gave equal space for the air to leave then dose not matter if you have more intake fans. and the flow across the parts are very important. but the work positive pressure is used incorrectly if you do have space for the air that you intake to leave. because positive pressure mean that you have raised the pressure inside the case to be higher than atmospheric pressure. it is possible to do this but you would really have to have a good sealed case as you stated.

the location for the fans and the exhaust is the most important. will not cool very well if the air comes in the bottom and also all leaves from the bottom...

A little test: Removing PCI slot covers DOES make your GPU cooler... (pic heavy)

ebhsimon

REAPER XD

ebhsimon

Deni

ebhsimon

Deni

ebhsimon

seross69

ebhsimon

adre

VindalooJim

ebhsimon

doyll

TiezZ BE

FastMHz

francisw19

ebhsimon

miklkit

doyll

seross69

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