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750D Airflow - Add bottom fan(s)?


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I love my new case, and it's much quieter and roomier than my Antec 1200... but the lack of airflow right now is a bit of a problem. Running the case fans at anything less than 800 RPM of their 1200~ max creates higher than desired motherboard temperatures. Even at 800 RPM, the PCH and DRAM are at about 40-45 degrees while the intake is 22. If I bump the fans to max, the temps drop to 35. The front panel being on or off doesn't make much difference.


I have three probes located throughout the case right now. The first is right behind the top intake fan - 22 degrees as I stated earlier. The second probe is roughly 6 inches directly to the side of the intake probe, right past the SSD caddies - it reads 24 degrees (bumps to about 27 during gaming). The last probe is between the two GPUs, resting against the fan shroud of the top card - it reads 26 degrees and bumps to about 35 during gaming.


I have my H100i fan speeds at roughly 1200 idling (cold boots water is at 27~ degrees, but right now 30). Water temps around 35 degrees net 1500~ RPM, and 40 degrees 2000 RPM (loud, but I'll be gaming anyway).


I only have the three included AF140L case fans, and the H100i in P/P exhaust at the top right now. My two 670's are not blower cards, so heat is coming from them. They're getting replaced tomorrow with two 780 blower cards, so hopefully that'll help.


I am considering adding a fan to the bottom HDD cage area; however, it is not filtered (which is disappointing). Does anyone know of a simple and effective way of doing this where it would be easy to clean? I don't really want to have to lift the case up to remove the filter (maybe a filter on the back of the fan inside the case?), but if that's necessary then so be it. I just don't know the best way to go about doing this.


If anyone also has recommendations on what to do with fan speeds of my current setup, let me know. The case fans are set to idle around 800 RPM and ramp to max when temps start going up - they're not loud so their RPM isn't an issue. I don't think increasing the H100i's fan speeds will positively affect the airflow of the case, but I could be wrong.

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I got a dremel and cut an 120mm hole in the side of my panel and then drilled the holds for the screws and then I bought a fan guard for $5 from newegg and did it that way.





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Looks clean - don't think I could pull that one off. Funny how we have the same case and PSU though!


There is definitely an airflow issue with cards that don't use rear exhaust and this case...


Here is a temperature comparison of a 20 minute benchmark of Valley with my 670 OC Windforce editions and the 780 SC's with the Titan cooler from EVGA


670s -- 780s


H100i Water temp - 42.1 -- 38.7

CPU cores temp - 64-69 (66avg) -- 62-65 (64 avg)

GPU 1 temp, fan speed rpm/% - 82, 3420/64% -- 83, 2730/64%

GPU 2 temp, fan speed rpm/% - 83, 3510/66% -- 81, 2570/62%

---Below temps measured using Z87 Sabertooth sensors

Motherboard - 45 -- 36

DRAM - 56 -- 46

PCH - 60 -- 54

VCORE - 55 -- 55

PCIE 1 - 60 -- 64

PCIE 2 - 55 -- 63

SATA 6G - 57 -- 67

Sensor 1 (intake) - 24 -- 22 (no change in ambient temp)

Sensor 2 (between SSD caddies and GPUs) - 36 -- 25

Sensor 3 (empty PCI slot between GPUs) - 40 -- 50

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  • 1 month later...

So, I went ahead and added two AF 120 fans to the bottom with some magnetic fan filters. I also switched the rear fan to intake. The front fans, rear fan, and bottom fans are all intake. The exhausts are the GPUs and the H100i, along with the vents all along the back and top of the case.


I attempted to calculate differences of intake/exhaust CFMs using this setup, but I have no clue what the blower style GPU fans are capable of pushing... so this is pretty much useless.


I've played around with fan settings a bit, and think I've got it where I want it. Can't comment on noise right now as I haven't had a chance to sit in silence due to the family.


All of my temps seem to have improved, minus the DRAM. I'm guessing there isn't much airflow because I had to relocate the HDD cage directly in front of the top intake fan. Could add the Corsair fan there, but it's not the best looking thing out there, so I'll hold off for now.


Same test ran as above. Cards are also OC'd higher than before, hence the major increase in fan speed on them.


Before -- After


Water temp - 38.7 -- 33.9 (w/ much lower fan speeds)

CPU temp - 62-65 (64 avg) -- 40 (core 4) -60 (core 1) (50 avg - no idea if RealTemp is getting good measurements)

GPU 1 temp, fan speed rpm/% - 83, 64% 2730 -- 82, 79% 3310

GPU 2 temp, fan speed rpm/% - 81, 62% 2570 -- 79, 76% 3160

Mobo - 36 -- 32

DRAM - 46 -- 57

PCH - 54 -- 50

VCORE - 55 -- 54

PCIE 1 - 64 -- 62

PCIE 2 - 63 -- 61

SATA 6G - 67 -- 66

Sensor 1 - 22 -- 21

Sensor 2 - 25 -- 23

Sensor 3 - 50 -- 64







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