IMAC INTEL HD problem

[maclinic]

Hi all,
i am experiencing this weird problem with my imac HD.

When starting up from the internal HD my imac would become very slow and sometimes eventually freeze up. If i booted from my external HD with all the same apps and docs, the Imac functioned perfectly.

So I instantly thought of a HD problem and installed a brand new one.

After reinstalling Snow Leopard and resetting all my docs through my Timemachine backup, the problem reappeared when starting up from the new internal HD.

If I start up from my same old External HD everything works fine.

Does anyone have a clue of what could be wrong with my Imac?
Could it be an HD controller? Because it's starting to look as if there's a problem in the communication between the HD and the logicboard. A problem that does not occur when starting up from an external HD.

If anyone could help me out one this one it would be greatly appreciated.

PS could external HD's connected to the computer through USB at startup be the culprit?

Thanks all

 

[djdawson]

I'd run the extended hardware tests. They're on one of the system install disks that came with the computer - just hold the "D" key down while you boot from it.

 

[chscag]

After reinstalling Snow Leopard and resetting all my docs through my Timemachine backup, the problem reappeared when starting up from the new internal HD.

You've probably got software or a driver on that hard disk which is slowing it down. The above method you used merely transferred the problem from the old disk to the new one. Completely erase the internal disk, format it and reinstall OS X clean. If the slowdown problem persists, then it's likely caused by hardware, however, if the machine boots quickly and runs normally, you'll know that it's being caused by software or some driver.