For the last month or so I'm plagued with often, yet unexplainable spikes to 100% CPU load. Usually then Task Manager shows one or two processes taking 50%+ of CPU (not always the same: svchost, bitdefender/avira, task manager, explorer.exe, chrome, WMP etc.)

I reinstalled Win, switched from avira to bitdefender (avira slows with newest .NET installed, so thought maybe that), did a clean install (suspected malware, virus), got rid of flash (as even web browsing was bad experience), even youtube could become choppy - but no change. If left in idle, no spikes.

Replaced HDD in NOV'14 (previous one died in a crash accident - wife dropped laptop on the floor, causing hdd to detach, fall out and suddenly stop on the wall after several rollovers), so new one is 7200 RPM, 1TB 32MB cache HGST.

Weirdest part is that it started month ago or so. I know the system is old, and having NV160 on board means expiration date is already set, but I'm thinking graphics issue are somewhat Boolean in nature and with incubation in days on the outside, not months... So something else.

Anyone had similar experience? Or maybe some tips on concentrating efforts?

EDIT: More details on system. Win 7 Pro x64, 4GB RAM, T9400 2.54 GHz, Nvidia NV160 256MB.


Thank you all for your insights. But it looks like hardware malfunction after all. Thank you @LogicDaemon for suggesting HDD settings check. I have no idea why I stopped monitoring my HDD (Had HDSentinel for that), but in hindsight it was an error, which unveiled when installed said application.

HDSentinel reports 527 reallocated sectors and 497 weak sectors awaiting reallocation, with overall health indicator of 13%.

It looks like system was recovering bad sectors and that's why it clogged the system. However, it's beyond me why it showed specific process hogging CPU.

Anyway, looks like warranty job for the HGST.

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  • GJ finding it. Wasn't one of my guesses, never saw CPU spikes due to HDD BAD's. I've learned something new. But note that 527 remapped sectors isn't something necessarily lethal, though undoubtedly a bad sign. I've seen an HDD with ~1000 remaps working over 3 years (remaps number wasn't changing over time in my case). If number of bads stabilizes, this HDD may serve in an USB box for long time. – LogicDaemon Apr 24 '15 at 15:27
  • My take on this - since HDD BAD's stabilized since, and system runs well this last several days - is that the bad sectors were in the system/programs area and it had to recover (or at least try to recover) data stored there. I don't have another explanation of the phenomenon - it quite suddenly started and as suddenly stopped and only change is 0.5k bad sectors. And I have some issues that link to corrupted driver files that weren't there before, as well.. – AcePL Apr 30 '15 at 15:22
  • First, is it possible that BADs were in system/programs area. But you can't say for sure. After remap, OS will see no defect sectors, won't stuck on them, no difference if they "hit" programs or data. Second, from my experience, few days isn't enough to say if it is stabilized (i'd rather be cautious in next month or two). By the way, if your HDD is still under warranty, you can try to replace it. – LogicDaemon Apr 30 '15 at 15:41
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    Well, the operative word is "after". ;) The issue probably was "remapping now" when system was choking. And I've seen the bad sector count climb by 2-3 a day. This would correspond to month of several jams a day. But I agree with your assessment - drive is fully backed up and warranty claim is already in the system. – AcePL Apr 30 '15 at 15:46

Svchost.exe is a container for services. It's worth checking if it's the same service that is regularly spiking CPU use.

Look inside svchost.exe instances either with SysInternals Process Explorer or from the command line with tasklist /svc

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  • svchost most often popping up are one associated with netsvcs group and LocalSystemNetworkRestricted. So while I'm irked by need to assign cpu to process responsible for music sharing over network (I assume it's including BT headphones and transfer to phone as well) I;m not worried by rogue services there. – AcePL Apr 24 '15 at 14:13

Chances are your laptop is simply becoming very old. Most of your computers components simply can't keep up with the demands of Windows 7 and passive antivirus programs. If you really don't want to spend money on a new laptop or to upgrade the CPU or GPU, or you can try changing your theme to Windows Classic. If even that isn't helping much you can either put up with it or change the operating system, the former being more difficult but may be beneficial. If you were to switch to a Linux based system such as Ubuntu you won't "need" an antivirus program as most viruses target Windows and Mac based systems. However there are less programs on the market for Linus to suit your needs. However most Linux systems are far more lightweight than the typical Windows 7 and are relatively easy to learn.

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  • I was thinking along the same lines, but... I am an occasional gamer, and while quality is not great, it is sufficient for some of my favourites (Civ4, Civ V, CODMW (1,2,3), MOH (from 2010), Far Cry and GTA:SA). It is, or should I say was smooth on medium or high details (depending which game). It's no longer the case. Those same games that ran fine all the time in February now grind to a halt after 5-15 minutes. And system is marked as "Designed for Vista". I think it is more than sufficient to run win 7, don't you? – AcePL Apr 24 '15 at 9:45

My guesses:

  1. HDD transfer mode degraded from DMA to PIO.

    Usually this is due to bad contact or semi-broken cables. When in PIO mode, any HDD access takes a lot of CPU power. But if HDD is connected with hard-soldered-to-board slot, hardly this is the reason.

  2. Overheating and throttling due to dead cooler.

    If CPU is overheat, it will drop frequency to lower power consumption and cool down. On old laptops, coolers often work out of their resource and then eventually stop. So, when CPU load raises, it overheats, and drops performance.

    Also you can open resource monitor (it's included with windows: Win+R, perfmon /res, Enter OR use link on Performance tab of task manager). It also shows current CPU frequency, and will show throttling if it's happening. Or use something like CPU-Z.

  3. Bad drivers.

    Old laptop means Dell isn't providing new drivers for it anymore. But Windows still get updates. Maybe one of drivers conflicting with one of updates. Check for newer drivers from OEM manfacturers. If this is the case, there must be no spikes in safe mode.

    Also consider that different spikes (from different processes) may have either one, or multiple independent causes (maybe you just didn't notice that spikes before UI slowdowns began). Try comparing their length and form before making assumptions.

  4. Just in case. Check powersave mode and apps controlling it. Maybe some app decides that it's time to reduce power usage and puts CPU to powersave mode.

  5. Worst but possible. There are electrolytic capacitors in notebook

    These capacitors have limited lifespan, depending on temperature. With time, they loose capacity, and it may cause instability of power supply and signals amplitude. This can lead to errors in data transfers, which will cause re-transmissions to occur. In some cases, this re-transmissions counted as "busy" CPU time, thus causing miscalculation of CPU usage by process and overall slowdowns.

    If this is the case, it's time to replace notebook.

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    Ad 1. Nope, active UDMA mode: 6 ad 2. 55 C on idle Ad 3. Dell is notorious for not workin well with OEM drivers. But I think it's ok. Updated recently all available ad 4. Still checking, but looks ok so far. ad 5. Possible, need to check. – AcePL Apr 24 '15 at 14:07

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