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pci slot covers: airflow question

Posted: Mon Oct 30, 2006 4:05 pm
by outoftune
I am wondering what it would do to the airflow in my system if i had the pci slots removed.
i dont have a front intake fan, just an exhaust and the bottom fan of my PSU. is it better for airflow to have the pci slots open or closed? i am thinking of maybe just having the one below my videocard open....

Posted: Mon Oct 30, 2006 6:38 pm
by Chocolinx
Generally people open on PCI slot, the one under your video card. This helps air get to the video card. I think opening anymore wouldn't make a difference. At least in my system I've opened 2 for now when I opened up 4 it did nothing for my video card.

Posted: Tue Oct 31, 2006 9:32 pm
by Trunks
I have an Antec Sonata (1) case, rear fan triggered to only come on at 110F system temp, and a neo PSU, ninja+, acoustipac. Removing all of the slot covers made my machine louder (noise from the fan on the video card was substantially audible, My CPU peak temperature went from around 108F to 95F and my PSU went from around 110F peak to 123+ peak. I think that in my case it made a huge difference. With the slot covers on cool air was pulled in the front and rear fan area and easily removed by the PSU. With the slot covers removed the system temp and the PSU temp were much higher, but the CPU cooler. Over all the PSU fan was on more because (I think) it had to move more air.
I leave my slot covers on, less direct sound path for Video card and hard drive noise, and I think the volume of air my computer “movesâ€

Posted: Wed Nov 01, 2006 5:03 am
by datapappan
Removing the pci cover results in two things (if you don't have intake fans):

1. Case impedance is lowered, so more air is moved by the fan, OR you can lower the fan rpm for equal air flow as before.
2. Air paths will change, can be good or bad. Naturally, air past the video card etc will increase, at the cost of previous air paths, maybe the HD will suffer?
3. OK, one extra - you get yet another sound path out of the case, if your graphics fan rpm wasn't lowered, sound level might be higher (depending of what part is the loudest.

If you do the same with intake fans, you get an warm air exhaust effect, similar to using the AC coolers, but not with 100% effectiveness, i.e. not all warm air from the GPU is exhausted directly, but might be used as intake air for the CPU.

/ datapappan

Posted: Wed Nov 01, 2006 7:58 am
by outoftune
hmm well since i have a passive video card (radeon 9200) that i don't run too hard (never do any gaming, maybe the most it does is in photoshop or protools), i think maybe opening one slot might help it.

i am going to be putting my drives in gel pack enclosures so that will take care of their noise. i plan on switching my 7000b alcu for a ninja ducted to the rear fan, using the PSU fan as the main exhaust for the rest of the system. I have no intake fan, i might try one if i need to.

so once i have added the setup i just mentioned, opening the PCI slots will help to get more fresh air to the PSU fan, correct?

Posted: Wed Nov 01, 2006 8:05 am
by EsaT
Unless cooling of HDs is arranged other way I wouldn't take slot covers away.
In many cases cooling of HDs depends on airflow of exhausting back fans coming in from front of case.

Posted: Wed Nov 01, 2006 9:08 am
by Trunks
I think the real think to do is just try it. In my case It had a really strange effect of substantially lowering the CPU temp and raising the PSU temp higher than I was comfortable with.
I think if you have gone to the trouble and expense of Acousticpak, you don’t want to open a direct sound path. But this may be very subjective depending on where you sit relative to the machine, if you can see the rear, if it is under you desk…
Also I found a hard drive sound reduction when I “acoustipakedâ€

Posted: Wed Nov 01, 2006 11:17 am
by outoftune
i will give it a try to see what happens once i get the ninja. putting some acoustipak or foam over the pci slots sounds like a good idea.

thanks to everyone for the input.