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A couple days ago I shut down and unplugged my Win 7 PC to change outlets on the power strip. It was running great with no issues or complaints. Startup times were like a minute at most and performance was snappy. No new software installed, nothing changed on my end.

When I switched plugs and booted back up a few seconds later it got stuck on the BIOS screen (I thought). I waited for a couple minutes but it didn't budge and didn't respond to me hitting F12 to enter the BIOS (just to see if it had crashed, didn't actually care to enter the BIOS). I restarted several times with the same result. I tried switching the plug back, negative. Tried leaving it unplugged overnight, no change.

I finally just left it on the BIOS screen for a while and after several minutes it started the OS initialization. Unfortunately this took forever and it was like watching it in super slow-motion. When it finally booted up everything continued to be in slow-mo, when I open or close windows they fade in and out. The mouse moves normally and internet browsing is not affected, but this is an HTPC and I can't watch TV on it anymore because the picture is too slow.

I ran the disk check and didn't get anything, and everything I can tell seems to be fine but I really don't know how to do any diagnostics, there doesn't seem to be any diagnostic tools set up on my PC. I am confident it isn't software or hard drive related since it affects the computer before the OS even boots up. I am thinking it has to be motherboard or memory related?

Any advice on how to check that for free (I am poor, no funds available to spend on this), or any other suggestions?

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1) First go to the BIOs. Check all values including if the caches are disabled. (If CPU cache is disabled you will get the symptions you described). If that fails try resetting to defaults and boot a liveCD. (You can have someone else burn that on another computer). See if the liveCD (on CD or pen drive) is as slow. If it is -> HW problem. If not -> software problem. Finally, check if the CPU fan did not drop off. Overheating protection can cause significant down clocking, but just switching a plug should not cause that. (moving a PC at the same time just might have though). –  Hennes Sep 9 '13 at 0:02
    
You CMOS battery may have died and restored your BIOS settings to default (and therefore not optimal). If so your system clock would be off in the BIOS. I would follow @Hennes advice and also run a memtest and hard drive test as well if it doesn't resolve the problem. Heat would also explain this problem. Check all fans are spinning when you boot. –  Moses Sep 9 '13 at 0:04

2 Answers 2

In addition to what @Hennes and @moses suggested about checking your BIOS settings and CMOS battery, here is what I would suggest

  1. Try swapping out your Graphics Card if you have another one available. The fact you can move your cursor around normally, but other things such as video are peforming slowly now lead me to believe it could be GPU related.
  2. Try swapping out your Power Supply if you have another one available. This is an off chance, but you mentioned these issues started after you changed power sources. Maybe your PSU is going bad and not supplying enough power.
  3. Disconnect everything you possibly can. The only things that should remain connected to the motherboard are the RAM, CPU, Graphics Card (if not built into the M.B.), the Power Supply, and a Keyboard. Boot the PC and see if you still have the issue.
    • This will rule out any hard drives, optical drives, and periphreals.
    • If the problem still occurs, and you can rule out your PSU, GPU, and RAM, then it's a good bet your motherboard is bad. In my experience, if your CPU is bad you wouldn't even be able to get to POST.
    • If the problem does not persist, connect each device one at time until the problem returns, then disconnect it and repeat to confirm it wasn't just random chance.
  4. Download the Memtest 86+ Live CD image, or any other Live CD that contains it such as SystemRescueCD or Trinity Rescue Kit (both of which aren't bad to have around anyways). This is a pretty reliable test for determining if your RAM is bad, though I doubt bad RAM is your issue because usually bad RAM doesn't just result in slowness, it results in full on system crashes (i.e. BSOD's or unexpected reboots). There is a guide on SevenForums that explains how to use Memtest 86+.
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Are points 1 and 2 actually possible? Surely both the mouse and the UI are rendered by the graphics card. In any case, why would a graphics issue affect the BIOS? As for 2, if the PSU is failing then the PC would not start at all right? Either it has enough power to run things or it doesn't, how could it give this halfway scenario? –  terdon Sep 9 '13 at 4:57
    
@terdon, I can't say it at 100% as I've never seen either actually be the problem. However my logic on point 1 is this: As I understand, the CPU is responsible for polling the cursor position, and the GPU is responsible for rendering. On the other hand the GPU is usually responsible for most aspects when it comes to video. My logic on point 2: If the power supply is putting out a lower voltage than it was designed to do but still enough to run the computer, then the CPU and GPU will be under-clocked. Underclocked CPU/GPU will result in lower performance. –  druciferre Sep 9 '13 at 14:30
    
My personal bet though is that @onefatfrog will end up having to replace the motherboard. I've seen issues very similar to what he describes (especially the slow POST) before, and in each case it wasn't until I replaced the motherboard that the problem went away. All of the points I've posted though will at the very least help him narrow down the component causing the problem. –  druciferre Sep 9 '13 at 14:33

You should try http://www.hdsentinel.com/download.php . Sounds like a bad drive if it's not the cooling. Also make sure you don't have a disc in the optical drive or a usb drive plugged in.

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Can you give more details to how this link is relevant, For more information on answering questions please see How to Answer –  50-3 Sep 9 '13 at 4:32

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