If you have really crappy cooling right now it will make a big differance. Normally with good cooling you should run 2-3'C. Even 3-5'C warmer is OK. If your room temp is 22'C and you run 40'C full load, then a side and top fan could drop your temps 10'C or more, but so could cleaning out the dust, tie loose cables out of the way of the airflow and removing restrictive fan grills and installing wire grills (like used in most blowholes). If you have one fan front and back (not counting the power supply fans), you should be able to get at least adiquate temps. If not this will drive up the temps of all the parts in your computer including memory, CPU, graphics card, hard drive, CD... and some of these componants can be pretty sensitive to high temps, causing stability issues or even early failures.
My case has 2 fans in front, 1 in the back, 2 in the power supply and one on the CPU. These are all low RPM (2500) 80mm fans that are very quiet (30db or less). I have a large passive heatsink on the northbridge and the stock heatsink on my GeForce4 Ti 4200 (whick is pretty quiet). My case temps are usually about 3'C above room temp full load and the passive heatsink on the northbridge stays about 30'C. Some said these heatsinks kept the northbridge as cool as the stock heatsink and fan, but it actually runs about 5'C warmer, but at least I do not have a fan that keeps failing on me (I had to clean and oil the cheap thing about every 3 months to keep it from grinding or stopping). My heating is an old GlobalWin FOP32-1 that I mod'd to fit an 80mm fan (spred the fins out a bit). I use Arctic Silver II and the fan generates 34CFM at 30db (2500RPM) and my system stays at 32'C idle (with CPUCool running) and about 42'C full load (almost the same as my northbridge). My room temp is 22 and my case temp is 24'C.
AMD Phenom II x4 945 3Ghz | ASUS M4A77TD | 2X WD 1TB SATA 2 hard drive | 2x2GB Corsair XMS3 | nVidia GeForce 8800 GTS | ATI TV Wonder Theater Pro 550 | Antec P-160 case | Antec 650w Earth Watts | LG Blu-ray Super Drive | LG DVD RW | Windows 7 Pro
i've got 1 on the bottom front, 1 on top and 1 out the back (plus the PS's) all 80mm. i also put 2 on the side right above the CPU and video card, but i don't have these on, cause i figure it would only screw up the airflow (from front bottom to back top). but they do provide the CPU fan to draw air directly from outside the case.
i've got an althonXP 1700+ @ 1560mhz, with a vantec CCK-6035D and AS2 (changed the fan from a loud assed 60mm 7000rpm delta to a 5000rpm from a volcano2). motherboard moniter says the CPU is running at 50-51 full, 42 normal. 19-21 for the roomtemp (or case temp i guess).
i'm going to give it a clean out today now that i think about it.
AMD XP-M 2500+ @ 2200 (200x11), 1.65v Thermalright SK-7 w/ Thermaltake Smart fan2 Abit NF7-S v2.0, Forceware 5.10 OCZ 1.5gb OCZ PC3200 2.5-3-3-10 Radeon 9800XT 128mb w/ Zalman VF-700cu Maxtor 250gb SATA HD LG DVD-RWPioneer 10x DVD Enlight 7250 w/ 2 80mm Enermax Noisetaker EG495P-VE SFMA Logitech Z2300 Speakers Samsung 753DF WinXP Pro SP2 DX9.0c
I've got 4 Akasa 80mm fans in my case: 2 at the front and 2 (with blue LEDs) at the back. Then there's 2 80mm fans on my PSU, and finally the Globalwin heatsink has an 80mm fan on it.
All fans run between 2500 and 3200 rpm, with a total of about 190 CFM moving through my case.
Case temp: varied with load on CPU - usually between 29 and 38 deg. C (I've got a warm room )
Idle temps for system shown below: 39 deg. C
Load temps: between 40 and 49 deg. C
I added my GF4 yesterday, a sound activated neon light today and rebuilt the whole thing from scratch. Doesn't seem too bad seeing as I had to move the HDD to the bottom of the case cos my GF4 is a very big card . This means that the front fans are blowing across it, causing warmer than normal air to be blown from the front
Still, not bad temps, I reckon
A64 3200+ Venice | XP-120 | 1024MB GeIL Ultra PC4000 | Asus A8N-SLi Deluxe | Connect3D ATi Radeon X800 XL 256MB | 2x 250GB Maxtor DM+10 (RAID-0) | LG Flatron L1710B | 1999 Ford Mondeo Ghia X 2.5 V6
"Oh Lord, grant me the senility to forget the people I never liked anyway, the good fortune to run into the ones I do, and the eyesight to tell the difference."