Getting mb and cpu heat warnings

The first thing to do would be to remove your heatsink and fan unit and clean off any excess thermal paste from the old application from both the HSF and the CPU heatspreader. Then apply a new layer of thermal paste and re-install the heatsink. That may help with your CPU temps.

Poor airflow would be the more likely cause of motherboard overheating. Ensure that all of your fans are clean from dust etc. That being said, if the sensor reports that one fan is not spinning when it is then it is also possible that the temperature sensor on your motherboard may be faulty. You can try removing the side panel to allow cool air to get to your motherboard. See if this makes any difference. In the past, I have even blown cool air onto the motherboard with a hair-dryer (on cold mode) just to check whether or not the sensor is stuck.

Other than that, you can also check out the guide in my signature below. It should offer you a lot of help when dealing with overheating issues. Hope this helps and good luck!

Thks moody89,
I applied new Thermal Gel to the CPU and that got it's temp down but the MB issue persisted. (Ordered new MB Asus P5KPL) installed it yesterday and PC would not even start. Took power supply to a PC repair place and had them test it - came back OK.
The problem turned out to be a faulty Graphics Card, it was over heating and this resulted in heat transfer to the Mother Board. (Strange as the Graphics card was Asus and the Diag. overclocking utility comes back "VGA card is okay")

Forgot to mention, everything now coming back at acceptable temps was:
Old CPU temp 71 oC
Old MB temp 50 oC
Now
Current CPU temp 41 oC
Current MB temp 35 oC
With old ATI Radeon 9250 Graphics

And I have a spare MB, so I guess it is time to start a building a new PC.

I'd look into an extra case fan or something.. If the GPU overheating is causing those kind of temps then its like there is no air flow at all.

You say the new motherboard wouldn't start at all before you took it back out?
If you can list your full specs currently, and also what is the new motherboard model? Then maybe we can help with that issue and future parts to go with the motherboard that are fully compatible.. unless you're going to send the board back.

Thks blckhaze,
yes the new Motherboard did not want to start, all fans spun once then dead, I have tested the new MB with the Radeon Graphics and it works fine. I am guessing that the new P5KPL Mother Board has some sort of sensor that detected a problem and shut everything down. I am not going to bother sending the new MB back, all cables still in bags, untouched etc. but you really do need a spare PC. (As two days without one, showed me. Had to phone a friend and get him to order the new MB, life is sooo much simpler with the internet and cheaper too   My backup PC (a laptop) is up the spout and I think needs a CMOS reset but that is for another thread.

The old Asus GPU was definately the problem as I did the old disconnect/remove to see what starts. (Removed all PCI cards, disconnected all Hard drives/CD's, started PC with CPU got beeps, switched off, added back memory etc until I got to graphics card and one spin of fans (2 chassis and CPU fan) then dead with no beeps, no flashing MB lights/just normal green MB power light.

In terms of air flow I think the hot weather last week must have pushed the GPU over the edge, although the card had it's own fan (Asus 9500GT 1GB DDR2 DVI VGA HDMI PCI-E) and its PCI-E slot is situated near the two chassis fans. I noticed an "extra connector" on the MB for a power supply fan which is not in use as my power supply's fan is intergrated in the PSU. I will spec out a oversized side fan as I have air-intakes there. Otherwise it will have to be a PCI slot fan or below the HD's.

Thanks everyone for your help.