H100i V2 problems

I upgraded from an original H100 i got in 2011 for my Sandy Bridge 2500K cpu on a Maximus IV Extreme Z board. Fry's had a sale for $60 on Corsair factory refurbished H100i V2's so I picked one up last week. I'm having a few issues...

The CPU backplate fits loosely even with the grey Intel standoffs for 1155 tightened all the way down. When I hand tighten the mounting screws on the waterblock all the way down by hand only, I get a CPU error and the PC won't boot! I then have to loosen the screws a lot in order to get it to POST and go into the BIOS. Once in the BIOS, the idle temp is 87 celcius! My PC then starts shutting down at 90 c before I can even get to windows. The pump header is plugged into the CPU fan header as instructed by the manual and online videos. The fans are spinning at full speed and plugged into the Y splitter included with the H100i V2. Either the block is not making proper contact with the IHS on the cpu or the pump is not running at full speed. I'm not sure. My motherboard doesn't allow CPU fan header voltage control. I'm not sure if i need to disable cpu fan monitoring or control to allow a full 12 volts to go to the pump. I also get CPU Fan ERROR when booting! It doesn't recognize the 3 pin pump header that's on the cpu fan header on the board.

My old H100 ran on a Sata Power connector at 12 Volts so it always worked properly for the past 7 years. I decided to change coolers because i was hearing a lot of sloshing in the unit so I assumed the liquid was evaporating after all these years. I'm also planning to upgrade to Z390 and 9th gen Intel CPU's very soon. I hope this cooler will work fine with the new setup but for now it's on a Maximus IV Extreme Z and 2500K cpu.

The backplate is supposed to be a little loose; that's normal.

If fully tightening the screws causes a problem ... there's something wrong. I'm not sure what that might be but they should be tightened down to ensure proper contact. If you adding something so that the backplate was "tight" ... that might be doing it.

The CPU Fan should be set to 100%/Full speed (see the Liquid Cooler FAQ, Section B). That will ensure that the cooler gets the full 12V of power that it requires. Anything else can cause issues.