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shotgun_banjo

New Member
Joined
Mar 16, 2016
Hi long time lurker here and just got myself into desktop pcs again after 20 years. So long story short I bought myself a pre-made system (yeah I know...booo me!) but the pre-made system is such a good deal that I cannot pass it up and if I build the same thing from parts it will cost me more money.

So the PC I bought is a Dell XPS 8900 with I7 6700k, gtx 750ti, 24 gig ddr4 ram, 2 TB hdd with 32 gig cache SSD, built-in wifi, raid controller. (only paid $890 for this - yes I know really cheap that is why I said I can't pass it up). Then I bought myself a 250 samsung SSD / 3.5" SSD holder with fan, ASUS GTX980 Ti OC Astrix, EVGA 750w G2, Titan Dual GPU fan, Noctua B9 fan, Bgears 90mm fan.

Everything works, the GPU, PSU and the PC is like a VW beetle with a Ferrari engine on it. The setup I did for the fans is as follows:

1. The mobo rear case fan (the mobo only has 1 case fan header) was relocated at the front of the case to act as intake as the dell bios won't allow you to control the fan speed as it is temp. controlled so I opted just use it as a intake fan and this fan rarely hits it's full RPMs so lets say it is pulling 25 CFM at regular use (fan is rated at 37 CFM).

2. The Bgears which has a CFM output of 88 CFM is used as the rear exhaust which is connected to the Titan GPU dual fan cooler (66 CFM) with it's own speed control. The Titan GPU cooler will pull-in air from the side grille besides the GPU as there are ample amount of panel perforations on the side panel besides PCI slot area. The idea is when I am rendering for longer amount of time which will use the GPU 100% for hours of rendering I can manually control the output of the exhaust fan and will exhaust the heat faster.

3. The Noctua B9 fan (38 CFM) will be situated also at the front of the case below the relocated mobo controlled in-take fan (#1). I manage to fit both fans at the front of the case.

So this is my dilemma...

Ambient Room temperature is 20°C

Scenario 1 - Positive cooling effect - Mid-noise level

Bgears fan at front of case connected to the Titan GPU cooler (running maybe 40% speed as that is the minimum speed I can set it to and maybe pulling-in 35-40 CFM of air), Noctua fan at rear as exhaust running full speed (38 CFM), mobo-controlled intake fan running at ±50% (only a guess) 20 CFM, Titan Dual GPU cooler running at minimum 30 CFM. So total of ±85 CFM as intake then 38 CFM as exhaust

I observed the following temperatures in the case using HWmonitor while running a 1 hour animation rendering using the GPU at 100%, CPU at 80-90%

CPU - average of 62°C then peaks at 78°C when it processes the final composition of the file (around 3-4 seconds only)
2 TTB HDD - max of 40° C
250 SSD - max of 40° C
GPU - max of 66° C (with custom fan curve-the GPU fan won't even run more than a few seconds to keep the temp down)

If I crank the speed of the Bgears fan to full power it is really noisy and temperatures did not really change maybe one 1°C at most

Scenario 2 - Positive cooling effect - Noisiest setup

Bgears fan (88 CFM) as exhaust connected to Titan dual GPU cooler running at max RPMs (66 CFM), mobo-controlled intake fan running at ±50% (only a guess) 20 CFM, Noctua fan at front as intake running full speed (38 CFM). So total of 124 CFM of Intake and 88 CFM of exhaust

I observed the following temperatures in the case using HWmonitor while running the same 1 hour animation rendering of scenario 1 using the GPU at 100%, CPU at 80-90%

CPU - average of 59°C then peaks at 72°C when it processes the final composition of the file (around 3-4 seconds only)
2 TTB HDD - max of 33° C
250 SSD - max of 29° C
GPU - max of 68° C (with custom fan curve-GPU fan runs at 68%-custom fan curve is set at 1°=% of fan speed then 100% at 80°C)

Then just for kicks....

Scenario 3 - Positive cooling - quietest setup

Same setup as scenario 2 BUT I keep the rear exhaust and dual GPU cooler at the minimum setting and this is what I got: (±91 CFM intake, ±35 CFM exhaust). This setup is also the quietest of the 3 setups I did.

CPU - average of 61°C then peaks at 75°C when it processes the final composition of the file (around 3-4 seconds only)
2 TTB HDD - max of 33° C
250 SSD - max of 33° C
GPU - max of 71° C (with same custom fan curve)

Most of the time it will run at 3 when not rendering (I render average of once a week for 12-16 hours non-stop). So which one is better? 1 or 2? Somehow I am leaning towards 2 but 1 has less GPU heat.

No I won't get myself a new case as I like the small form factor of the XPS. I just need to make sure I have the most optimum ventilation for the components using what I have.

Thanks!
 
Last edited:

Mr.Scott

Beamed Me Up!
Joined
Jun 9, 2013
Whatever your ears like best. Temps in all of them are totally acceptable.