Don't put WD-40 on the pins. I'd start by pulling out the sicks and cleaning the pins off with a q-tip and iso alcohol. Probably a good idea to clean out the slots now too.

Get Memtest64 and run it with both sticks. If it fails try it with each one by itself. If a stick doesn't past the test you should be able to get a new one under warrenty. Just start an RMA request and say it failed memtest64.

If its not your ram then its probably a poorly seated CPU. Remove the cooler, clean the paste off and carefully put the cooler back on without over tightening it, or tightening one side more than the other.

A few things to try out in addition to other folks' good suggestions:

• when it happens, after a hard shutdown, unplug the power cable, press the power button to discharge anything remaining, and then plug it back in and start. See if it consistently posts after you do this. This would indicate that a component is breaking itself but resets to a temporarily working state after a proper power cycle.

• monitor temperatures. Log them to file if possible. Overheating components might explain why workarounds only work sometimes. Maybe some of them just let the components cool down enough.

• just leave in one stick at a time and see how it goes. You can try to narrow down whether it's a stick or a spot that's broken by trying different slots with 1 stick and different sticks in the same spot.

• Not posting can look like a few things. Is it possible it's the video card / output breaking?

My cooler failed not long ago, the symptoms there were similar. Computer would freeze/crash and then wouldn't turn on until it cooled off.

Is it overheating maybe?

This could be any component, including MB, CPU, GPU, power supply. This could be damage that temporarily fixes itself once the thing cools down again. You'll want to remove as many components as possible, and swap out the rest with alternatives, or swap your components into another computer. Maybe you know someone you can visit to swap stuff out with?

Also, have you tried running memcheck86 on the RAM? There's also other diagnostic software for other components.

Just running a stress test like a benchmark might reliably trigger the problem, so you have a reproducible way of triggering the issue instead of just waiting for it to happen.

try using with single stick maybe? if it crashes try a diff one if that still crashes its most likely not ram.

Are you sure it's the ram? I had a bad motherboard that did basically the same thing. I was swapping pci cards around and it would eventually work. Turned out it was the flexing of the motherboard that got it working again.