CPU overheating, BIOS acting funny

[omegaglory1]

Hi all, I'm struggling to figure out the exact problem(s) with my rig. My specs are:

Intel i5 2500k 3.3GHz CPU

ASUS P8P67 motherboard

ASUS R9 290X graphics card

16GB HyPerX DDR3 1866Hz RAM

COOLIT ECO II C240 liquid cooler

Corsair 650W PSU

ASUS BIOS version 1850 (up to date according to ASUS site)

BIOS showed CPU temp going up to 88C, then auto shutdown kicks in. I removed the cooler and pump, gave them a thorough dusting. Unseated the CPU, cleaned it as well as the heat sink and applied new thermal paste (AS5). Made sure pump was cleaned, sitting properly and screwed in snugly. The cooler pump is plugged into PWR fan header on the board and cooler fans into CPU fan header.

Note: CPU was originally factory over clocked and left this way for 3 years or so. About half a year ago I reversed the over clocking. A couple of days ago I clicked F5 on BIOS to set default, just to make sure.

I installed CoreTemp on desktop to monitor temps. At first this was showing idle CPU temps of 35-40C, but would shoot up to 88-90C if I ran any programs or internet browser.

Most recently, I'm getting 88-90C as soon as I enter desktop. Auto shutdown is not kicking in anymore. BIOS still shows ridiculously high CPU temp.

Could my CPU or motherboard be at fault? Is there any way to check my cooler pump to see if it's working? It's connected to PWR fan but BIOS reads as n/a. Any help would be much appreciated.

[TheRandomness]

Hold your ear up to the pump, does it make any sound?

[Master Disaster]

snip

You got another hsf knocking about?

Sounds like your pump died.

[Plexter]

Did you have stock cooler for Intel i5 2500k? Just install it and see temperatures.

[omegaglory1]

Don't have another cooler so I can't immediately test if that's the issue. My rig was a custom build from PC Specialist so I've never installed a cooler from scratch by myself. Apart from making sure my new cooler fits inside the case and is connected to the motherboard, do I need to download any software or make changes in BIOS?

The sound from my fans get in the way of hearing the pump. What sound should I be hearing from the pump? Also, the pump's pin connector is on PWR fan on the board, is this the correct way?

[omegaglory1]

The pump does get warm. Is that a good or bad sign?

[A Guy Eating Cereal]

The pump does get warm. Is that a good or bad sign?

I would say good sign, but try and get another cooler and see if that sorts it, failing that underclock your cpu 

[omegaglory1]

A new cooler would be the most cost effective option right now. My current one (picured) is designed to screw onto the ceiling of my case. Can you recommend a good cost effective cooler and should I go with a non liquid model this time?