So I bought the Antec 300 Illusion recently and a MSI 970A-G46 mobo. The motherboard only has 2 3-pin fan spots (and the CPU fan too), however, the case came with four fans. Should I look into cables that split the fans up or a device? I found two options (below), but if you have a better solution, I would be grateful.
How many molex connectors does your PSU have? You can usually daisy chain the fans together with molex connectors if you're lacking fan connections on the motherboard. I guess another question would be if your case fans have both a 3-pin connector and a molex connector.
All 4 fans are 3 pin connectors, but the cable above allows for molex chains. My PSU should be fine, as its modular with room to spare, but would I be able to control the fan speeds in BIOS or would I only be able to use the toggle switch on the fan itself (L-M-H or L-H).
Anyways, it seems that you're saying to go with the chain of molex cables....
If you connect the fans to the 3-pin connections on the motherboard then the fan speed will automatically be adjusted by the motherboard. If you connect the fan to the molex connectors then the fan will be running at full speed unless you have some way to manually select the speed such as the toggle switch.
The fans are antec Tricool fans so they are meant to be set with the switch and simply hooked to a molex connector on the power supply. Setting them all on low will generally give you plenty of airflow. If you want to be able to set their speeds you will need to get a cable that goes from the fan header to the molex connector of the fan and set their switch to high. It is much easier simply to use the switches built into them.
edit: it would appear antec has since updated the twocool and tricool series to actually have motherboard fan headers(the ones in my 300 do not), but i would still stick with the molex connector to avoid splitters.
That sunbeam fan splitter does not permit any speed control at all, it runs all fans connected to it at full speed since the output voltage is set to be the same as the input voltage.