My PC is acting weird

My brother has a desktop PC with the following specs:

Intel Core2Duo CPU E7300 @ 2.66 GHz
3 GB DDR2 RAM (2+1)
ATI Radeon HD 5670

The PC was purchased quite a long time ago, though it saw some upgrades a few years back. The CPU was swapped, an extra 2 GB of RAM was added (it originally had one stick, hence the 2+1 configuration), and another 500 GB HDD was thrown in. The original 160 GB drive, which holds the OS, has been in there since day one. The graphics card was originally an Nvidia GeForce 8600 gt, but that died on him, so he picked up this Radeon card from a friend.

For a while now, the PC has been sluggish, and lately, it’s been freezing out of nowhere, forcing a manual reboot. Without any pattern, at totally random moments, the screen would just go solid white or blue (or some other color), the audio would loop with that stuttering R-R-R-R sound, and I'd have to force a restart. One day, he finally hit a BSOD during bootup, and that was it—it wouldn't start at all. It hits the Windows loading screen and then immediately throws a BSOD. Same thing happens in Safe Mode. I booted Linux Mint from a CD successfully, which led me to conclude it isn't a hardware failure yet, but rather that the Windows installation is corrupted. He was running a pirated version of Windows 7 x86 Ultimate.

Yesterday, I tore the whole thing down to the components and gave it a deep clean. The fans were barely spinning because they were choked with dust; the thing sounded like a jet engine. I reapplied thermal paste to the CPU using Arctic Cooling MX-2 and put everything back together. I pulled the 500 GB drive out and put it in an external enclosure since all his data is on there, and I swapped in a 250 GB drive that was sitting in a drawer. I kept the original 160 GB drive as the primary. When I powered it up, all the fans spun and everything seemed fine, but there was no video signal. I tried reseating the GPU several times and restarted the PC, but nothing. Eventually, after pulling the RAM and GPU again and reinstalling them, it actually worked. I'm not sure if that fixed it or if I just didn't seat the RAM properly during the first assembly attempt.

After that, I used gParted in Mint to format that 160 GB drive, then performed a fresh install of Windows 7 x64 (the legitimate version from DreamSpark). During the Windows installation process, I formatted the partition once more just to be safe. Immediately after setup, I ran CPUID hardware monitor and AIDA64; the CPU temp was around 40 degrees, which is great. I ran Prime95, and the max temp reached was 60 degrees, so thermals are definitely fine.

However, the issue persists. It didn't take long before it froze again; this time a white screen popped up suddenly, the music stuttered for about 5-10 seconds, and I had to restart. About an hour later, it happened again, but this time it was a blue screen (not a full BSOD, just a solid blue screen). Half an hour after that, it froze differently: everything locked up, the cursor just spun, and it felt like Microsoft Windows not Responding 😁 I restarted it and went to the kitchen while it booted up, but when I came back, the PC was running but there was no image on the screen. I forced it off and turned it back on; the fans spin, but after five seconds, it shuts itself down. I turned it on again, and for now, it's working.

I suspect something in the hardware is failing, but I can't pin it down. It could be the HDD, the GPU, the motherboard, or maybe even the RAM. CrystalDiskInfo shows the HDD health status as "Good," with 16,932 hours of runtime. For the second drive, it reports "Caution," but that drive was only placed in the PC yesterday (it was previously the 500 GB drive), so I doubt that's the culprit.

What should my next steps be? I suppose I should run Memtest86, HDTunePro, etc. Any advice? Or does anyone recognize these symptoms enough to know where the fault lies?

I’ve got a bad feeling about your RAM. Why don't you run Memtest86 all the way to the end and see if it flags any errors?

Ran Memtest86 from a USB drive, and it didn't flag a single error: View on imgur

Then there's HDTunePro:
View on imgur
View on imgur
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View on imgur
http://i.imgur.com/HdQvCm8.png

The only thing that looks even remotely suspicious to me are these Read speeds. If it isn't one of those, what else could be causing this?

I went through something almost identical on my old rig... most of the time it boilsolves down to components not being 100% compatible with each other, or even if they are, maybe some frequency, latency, or voltage setting just isn't dialed in quite right... That kind of freezing is what we call a "loop"—and I’m guessing your audio starts glitching out too (that weird 😬 sound), right? Honestly, my gut tells me it's the RAM, like the processor just can't keep up with processing all the data...

Anyway, why don't you try borrowing some RAM from a buddy and see if that fixes things? I'm really curious to see if it works... because this definitely feels like a hardware issue to me.
If it turns out the RAM isn't the culprit, then your motherboard is pretty much toast.

Unknown 😁 So, first the screen turns a solid color, then after a few seconds everything just freezes up along with the audio (that weird buzzing sound), and it stays stuck like that indefinitely until you have to hit the button to restart. Well, except for this most recent time where the OS itself actually locked up; I could still move my mouse—the cursor turned into that loading icon instead of an arrow—but no matter what I clicked, nothing happened, and I ended up with a Microsoft Windows Not Responding error, even though I've already done a clean install of Windows.

Maybe I should try testing the RAM sticks one at a time? Or perhaps it's a driver issue? The real headache is that these intermittent problems—the kind that aren't a constant "it works or it doesn't" situation—are a nightmare to troubleshoot. To make matters worse, my brother and I are both college students and the PC is at home, so he's only back every other weekend for maybe two days at a time. If it doesn't freeze while he's here during those two days, we can't really tell if we've actually fixed it or if we just got lucky because it needed another day of uptime to crash again.

The motherboard's probably dead, man. You should go check if the capacitors are even holding a charge

It looks like the CMOS battery might be dead, causing parameters to drift in the BIOS, both visible and hidden. If the motherboard is reporting voltages in the BIOS, check them. A 3.3V battery should read at least 3.18V. Anything less is an issue.
Alternatively, you could be seeing the same symptoms from a failing power supply. It’s perfectly normal; power supplies don't last forever. That is why it is always better to buy a unit with more headroom—perhaps 25% to 33% higher capacity than required. It provides a buffer that can last ten years or more.
If the motherboard was a budget model, which I would never recommend under any circumstances, cheap capacitors fail quickly. This leads to unstable CPU voltage and instability. You can't just measure that easily. It is better to pay $27 more for a quality motherboard that lasts a lifetime. And if this happens? I wouldn't buy from that manufacturer again. The motherboard is a critical component.

Lest I forget, if the BIOS battery is fine, try a Reset-CMOS.
If you install a new battery, it is safer to reset the CMOS immediately afterward. Otherwise, you may run into CMOS or parameter conflicts.

Thanks to everyone for the advice. Once I'm back home, I'll check the battery voltage, inspect the capacitors, and try testing the RAM sticks one by one to rule them out. I'm not quite sure how I'd go about testing the power supply, though it could definitely be the culprit; it’s likely one of those generic budget units you find in pre-built systems—classic move. Since this was bought as a complete setup and hasn't been upgraded since, the motherboard and PSU are both pretty old. It's been sitting in service for about 6 years now.

Actually, regarding those capacitors, it just occurred to me that I snapped a photo before I started cleaning everything out. You can see something here: View on imgur

They look fine to me in this shot.

So, how did you end up fixing that weird Unknown sound issue?
I'm going through the exact same thing—everything just freezes up and then you get that dreaded, infamous "Unknown" sound.
My PC was just at the repair shop because the motherboard died due to some factory defect. They told me replacing the board would fix everything, but honestly? It didn't do a thing. The same old problem is still hanging around.
It’s almost the exact same symptoms, just without those "Windows has stopped working" error messages popping up.
Same here—my old rig's been running for about 6 years now.
It’s the same thing every time—as soon as it starts loading Windows, the screen just goes black, or I get that blue screen, but not even a real BSOD.
It’s just the same... even in Safe Mode it's exactly the same thing. And now? Now I can't even get into Safe Mode at all!
So, I was wondering—how did you actually end up fixing that freezing issue with the "Unknown" sound?
Ran some tests on the memory and the hard drive, and everything’s looking solid—all green, zero errors!

I’m starting to suspect the GPU too.

If you're asking me, I'm not sure, which is exactly why this thread exists. I’ve only ever seen that specific error message about Windows failing to work once; otherwise, it’s just like what you're describing—a white or blue screen followed by total silence. It looks like we're dealing with the exact same headache. My situation is a bit different because the PC actually was running fine until something just snapped. I couldn't even get into Windows at all; I just kept getting hit with a BSOD. I ended up wiping the drive and doing a completely fresh installation of Windows, and while it works again for now, it still freezes randomly and then dies. There's no predictable pattern to when it happens; at least, I haven't been able to catch the trigger. After the fresh install, I ran about 500 different tasks at once and pushed the CPU to 100% to stress test the temperatures, and everything seemed perfectly stable. But then, much later, I'm just sitting there watching a video on YouTube and browsing the web, and suddenly—nothing. Just dead.

Forgot to include the specs!
CPU: Intel Core 2 2.66
RAM: 4GB DDR2
GPU: ATI HD 4800 1 GB
Motherboard: some Biostar board
OS: Windows XP Pro SP3
HDD: 1TB

The same thing happens to me whenever I'm gaming or watching TV—everything just freezes up and all I hear is that weird "Unknown" buzzing sound

And then I have to manually
_
But, get this: when I'm in Safe Mode, that sound doesn't happen at all. I can actually play for 5 or 6 hours straight without any freezing

Does it happen to you in Safe Mode too?

Lately, I've been constantly launching everything in Safe Mode—games, YouTube, TV—using a little utility called BootSafe

Steta st doesn't work on Windows 7

And yeah, just like what you're seeing, it's not happening all the time—it's more of an occasional
Unknown.

I've got the exact same processor. I haven't actually bothered testing Safe Mode yet. To be honest, I tried to boot into Safe Mode back when the machine was completely unusable—you know, right when those BSOD errors were popping up constantly—but I couldn't even get past the startup screen then. Since the reinstall, I haven't felt the need to try it.

Here’s how I see it: If your PC runs fine while you're in Safe Mode, then you can pretty much rule out a hardware failure; it’s almost certainly just a missing or buggy driver causing the headache. However, if the same thing keeps happening even in Safe Mode, and since you mentioned your C drive seems solid, we’re looking at either a memory issue or something on the motherboard—though if I had to place a bet, I'd lean toward the motherboard.

Hmmmm... so you're telling me it actually works when you're in Safe Mode? >, does everything run totally fine for you once you're in there? It’s possible that things seem okay in Safe Mode just because the drivers haven't loaded yet, so the components aren't really "talking" to each other properly... but as soon as those drivers are loaded, the whole thing falls apart immediately...

Once you get Windows installed, why don't you try installing the drivers one by one and testing everything as you go? Just be patient with it...

I dealt with this exact same headache on my old desktop back in the day, and it happened to me every single time... it turned out that basic hardware incompatibility was the culprit, and you wouldn't even feel the friction until the components finally recognized each other (which basically means as soon as the drivers are installed)

Man, I can't believe it's the motherboard again. 😢
It actually already went in for repair because the board had some kind of factory defect.
The motherboard was flagged back then since it was still under warranty.
They told me they were fixing it because of that Unknown sound, but honestly? It didn't fix a thing. The issue is still right there.
But wait, how do you even tell if the components are clashing? Like, if they aren't compatible?
Whatever, it's too late now anyway—the PC has to go back to the repair shop, no other choice.
I'm still getting the BSOD, and now I can't even get into Safe Mode.
So yeah, it's heading to service, but I doubt I'll actually get seen anytime soon. There's always something more urgent popping up ahead of me.

Roger Gray8 said:Hmmmm... so you're telling me it actually works when you're in Safe Mode? >, does everything run totally fine for you once you're in there? It’s possible that things seem okay in Safe Mode just because the drivers haven't loaded yet, so the components aren't really "talking" to each other properly... but as soon as those drivers are loaded, the whole thing falls apart immediately...

Once you get Windows installed, why don't you try installing the drivers one by one and testing everything as you go? Just be patient with it...

I dealt with this exact same headache on my old desktop back in the day, and it happened to me every single time... it turned out that basic hardware incompatibility was the culprit, and you wouldn't even feel the friction until the components finally recognized each other (which basically means as soon as the drivers are installed)

I'm not sure about Safe Mode; debugging a PC like this is a nightmare because I could spend hours waiting just for it to freeze again. What am I supposed to do for hours on end in Safe Mode? 😁 Besides, I was tinkering with the PC the evening before leaving for college, and I won't be home until the end of November, so I don't exactly have the luxury of time to run tests. Next time I'm back home, I'll have maybe a four-hour window to try and mess around with it.

I probably confused you by bringing up Safe Mode. Here’s the actual situation: this problem has been going on for ages. I’d constantly hear that weird "Unknown" sound coming from my brother's room, followed by a barrage of swearing, banging on the desk, hitting the tower, and so on. 😁 My brother used the PC like that for a long time until the Windows installation finally got corrupted—likely due to all those forced shutdowns. One day, he turned it on and was greeted by nothing but a BSOD. The Windows loading screen would appear, and then—boom—BSOD. Even trying to boot into Safe Mode resulted in a BSOD.

After that, I dusted out the case, reapplied the thermal paste, wiped the drive, and performed a clean install of Windows. Since then, the PC runs, though it still freezes occasionally with that same noise. I haven't actually tested Safe Mode.

Regarding drivers, I haven't manually installed anything; everything worked out-of-the-box following the standard Windows updates. The only thing I attempted was using the AMD autodetect tool to grab the latest graphics driver since my brother plays a lot of games and I wanted things to be tip-top. However, I didn't even get through the installation because the PC froze twice while the drivers were downloading. When I finally managed to launch the installer, it took forever. I eventually had to hit 😁 Cancel, but even then, the system wouldn't perform a proper shut down. I ended up having to hold the power button down until it died, 😁 and now I'm worried it's going to perform even worse.

crimsonfox20, we’re both looking at expensive repair shops

It feels like we're just tapping away in the dark because of this same issue
I actually read somewhere that this could be happening specifically because of those buggy ATI cards
And their glitchy drivers—especially once you get into that HD 4000 series and beyond
Sadly, mine falls right into that category
Trying to find a driver update for an ATI HD 4800 1GB is basically like winning the lottery
What a total piece of junk card😠🙂👎

Olivia Collins5, let's not get ahead of ourselves here. I've been running an ATI HD4770 in my setup for quite a while now, and honestly, I haven't run into a single issue with it.