I have a ASUS P7P55D-E EVO motherboard and a Corsair TX650W power supply. The 8-pin EATX12V power connection on the motherboard has 4 pins covered. The power supply says it can provide 8-pin or 4-pin support.
I am right assuming I should try to take the plastic off the other 4-pin connector on motherboard and use all 8-pins? Any idea why 4-pins are covered, the motherboard guide says to use 8-pins but the fact 4 are covered with plastic is confusing me!
According to Asus it is okay to remove the plastic cover and connect all 8 pins. The plastic cover is a convenience item for users who only have a 4 pin power cable. Asus does not say that in their owner manuals so it can be confusing. A couple of years ago I was in the same situation. I had to go to the Asus web site to find the answer.
While the 4 Pin connection is perfectly acceptable to use when the CPU is under 125 W power consumption, My recommendation is to use the 8-pin, if available. There is no downside to using the 8-pin connection.
Reason: It all comes down to IR drop.
4pin connection = 2 Parallel current paths, 8 Pin = 4 parallel paths. This equates to a lower IR loss at the connector and therefore a higher Voltage appled to the CPU Voltage regulators. NOTE: very small difference, but does favor the 8-pin connection.
At the higher Current levels for 125W, and greater, CPUs this IR drop (Heat) accross the connector Pins could melt the plastic holder when 4-pins are used - reason 8-pin connection is required.
Added: Misko195. The 4/8 pin issue was prior to quad core CPUs. The 8 Pin connection was added to accomadate the "Old" P4 extreeme ed processors and MBs that could utilize dual proccessors. Granted quads use more power than dual cores in the same family, but the requirements where based on current (Power) requirements, not the number of cores.