It is possible that jab-tech are putting their own connectors on the Y-Ls. It is easy to mistakenly put red on fan to red (5V) from the PSU, instead of to the Yellow from the PSU (12V). It should be red on fan to yellow on PSU and black to black. That will give you full speed. Some will connect black to red and red to yellow to give 7V for extra quiet - it is never wise to hard-wire for 5V as many fans won't start at 5V but will run at 5 if started from higher. Use the contact form on their web site to inquire (should have done that first) - you'll be pleasantly surprised at the promptness of their reply. If there really is an error, perhaps they'll send you a cheap tool to move the pins around - or since those fans are way cheap, they might just send you a properly wired one for free. Certainly not worth the cost to mail it back. Since those fans only use 0.3A (plenty safe to hook direct to mobo), I'd just cut the 4-pin molex pass-thru right off (unless you really need to use them).
The yellow wire on most fans is the Speed Sensor wire, red is + voltage, black is ground. I have seen the tach wire be different from yellow (white, blue etc.), but the voltage wires are pretty consistent.
PSU wiring is very consistent. Red=+5v, Yellow=+12V, Black=Ground.
.bh.
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