Is it possible for CPU damage to stop hyperthreading?

Replaced the motherboard on the Dell 17R SE - after it suddenly stopped working (bad charger probably to blame). Remarkably the new mb got it to working state again (thought it was gone) . The replacement motherboard seems to work fine - however, Windows only detects 4 core & 4 threads now - instead of 4C & 8 threads (same in CPUZ, and device manager, etc - it's a i7-3630QM).

I'm trying to resolve this:
1. I can't see any enable / disable HyperThreading option in the bios - and I've installed all the latest drivers / bios etc. So I'm thinking what could have gone wrong (maybe I forgot to reconnect a wire? or maybe it's a damaged windows installation? Is this more likely?)

Is it reasonable to assume the replacement motherboard is not the issue at least - given it works and could see 4 cores? Really weird issue.

Or is it possible that the CPU was damaged when the laptop stopped working originally - causing the only 4 threads situation? (I guess without HT I'll lose marginal performance - but I rarely use those heavily threaded apps - just glad the machine is mostly okay)

Thanks guys for your time!

 

I've had this happen a few times and just recently my i7-720qm only showed 3 cores in task manager after re-installing Windows. A power drain and a restart fixed it. Perhaps a re-seat of the processor if it is socketed. A re-seat of the RAM may also help. Not sure why this happens.

 

Check your BIOS settings, HT might be disabled at the hardware level there?

 

Can't seem to find "HT" option in the bios for some reason - I think I probably connected it wrong or didn't repaste properly.

 

no no, you can't connect wrong...either it works or it doesn't. Your BIOS may be locked and hiding the HT option from you. Best you can do is try to power drain and reseat everything.

 

Cheers - sounds like a weekend project to sort it out. Fingers crossed I remember where parts go to put it together.

 

Your BIOS may not have that option either and the problem might be unrelated to that. Not every laptop BIOS gives you the option to disable hyperthreading.

 

So repaste it is. What's a powerdrain? Just taking out the bios battery?

 

Powerdrain is usually done by removing the power adapter and main battery and holding down the power button for 20 seconds or so. That should drain all power from the board by depleting any charge remaining in the capacitors. Removing the little coin-cell battery will clear the CMOS, but that may be something you may want to try as well.

EDIT: I think a re-seat of the processor (and RAM) may help. By re-seat, I meant removing it, and re-inserting the processor in its socket, not repasting the thermal grease. Then again, you're gonna have to reapply thermal grease anyway if you're gonna re-seat the processor

 

Okay - that was strange.
1. Did a powerdrain. 4C4T
2. Repasted and reinserted the CPU. 4C4T
3. Realised that I didn't reconnect the subwoofer cable. Opened laptop again. This time took out Bios battery.
4. Magically booted up with 4C8T.

That was really weird.

 

Looks like clearing the CMOS did the trick. Glad it's working. Sometimes the CMOS memory can get corrupted and needs to be cleared.

 

Indeed, that is one great suggestion! Added it to my list of quick IT fixes