power supply/CPU/motherboard issues

[Ar-Pharazon]

Saturday morning I noticed a bad smell coming from the computer. I notice the rear (of 2) fans on the power supply was not running, so I shut the computer off. At that point it seemed to be working OK.

Went to Best Buy and got a new P/S (an 850W Thermaltake to replace the original 700W).

Got everything rewired and put back in, turned it on....nothing. I got the power lights and all the fans came on, but no BIOS or other ASUS screens and no HDD spinup. Double checked all the connections, especially the CPU power connection, still nothing.

As a precaution I exchanged the P/S for another one, still no dice.

Figuring something got damaged, I put in my older mobo (one I replaced due to not enough SATA connections), and got it wired up with minimum stuff (HDD's, RAM, CPU w/o heat-sync & CPU fan). I got into BIOS settings for about 1 minute and the thing shut down. Then it wouldn't power back up, I'd get a warning beep and immediate shutdown.

The main question is, does a quad-core CPU get SO hot that it won't run without a heat-sync and fan?

Or did it take some damage along with the mobo when the P/S went tits-up?

As it is, I went ahead & ordered a new mobo & CPU from newegg right away. I had been thinking about getting a newer, slightly faster CPU anyway. But if the other CPU could be OK, I'd like to put it into another machine I'm thinking of building with that older mobo.

Thanks.

 

[Jadzia]

The main question is, does a quad-core CPU get SO hot that it won't run without a heat-sync and fan?

I think this would be true of most high performance cpus. Even running idle, they'll be dissipating around 10 watts or more. Usually, the chips will detect a high temperature and shut down, but if the temperature rises very fast because there's no heatsink, they may not react quick enough. In short, never run a high performance cpu without a heatsink. Not even for a few seconds.

Or did it take some damage along with the mobo when the P/S went tits-up?

I'd tend to think that something other than the cpu has broken. But I may be wrong. If it is possible to try new psu with suspect mobo + cpu and no other hardware attached. Not even a graphics card or ram. Then see if that powers up okay. It would beep if it passes its POST, indicating that the mobo is okay.

Then try it with ram, then add graphics card. Find that component that stops it beeping.[/QUOTE]

 

[Ar-Pharazon]

I will try your suggestion. I tested with 2 out of 4 RAM sets and the HDD's and of course the video card.

How would I technically know if it powers up OK without the video? I know what it does with no RAM installed and I should see a BIOS screen at least with no HDD, right?

 

[Robert Maxwell]

Jadzia is correct. You never, ever run a desktop CPU without adequate cooling. A couple seconds is all it takes to make your multi-hundred-dollar chip into a paperweight. There is no guarantee it'll shut down fast enough to avoid damage.

 

[Jadzia]

It should give a single short beep which means "hardware all okay" If it gives more beeps or any other noises, or no noise, it means there's a problem.

But yes, the minimum you need to load bios is a cpu, and a graphics card if there is no onboard option.

But if the graphics card is damaged then it may not get to bios, even if everything else works. That would fail at POST.

 

[Alpha_Geek]

The main question is, does a quad-core CPU get SO hot that it won't run without a heat-sync and fan?

Yes. This has been the case since the socket 370 Pentium 4 ruled the world.

Never, ever, ever, ever run a modern CPU without a heat sink! Moore's law and Watt's law will cause the robotic equivalent of Darwin to attack your CPU.

 

[farmkid]

Jadzia is correct. You never, ever run a desktop CPU without adequate cooling. A couple seconds is all it takes to make your multi-hundred-dollar chip into a paperweight. There is no guarantee it'll shut down fast enough to avoid damage.

And not even a good paperweight at that. CPUs aren't very heavy, after all. Several years ago, in the early days of the AthlonXP/P4 battle, Toms Hardware posted an article describing a test they ran to see what would happen if you ran a CPU without a fan. They started the computer, then removed the heatsink and fan. The P3 froze up. One of the Athlon CPUs burst into flames within seconds. The P4 had the first real heat protection circuitry and dramatically reduced it's clock speed to keep the temperature down. It slowed to a crawl, but kept running. Modern CPUs should do a little better than the P4. So, your CPU is probably okay, but still, you should never run it without heat protection. Even though it probably didn't melt down, you may have significantly shortened it's life expectancy.

As for your motherboard, the blown PSU may have fried it. I had a PSU blow a few years ago. There was the loud pop of an exploding capacitor and a flash from the back of the computer and it was dead. I replaced the CPU, with a spare one I had that I knew was good. It still didn't start up because the motherboard was fried. However, the toasted motherboard killed the PSU, then that PSU killed another old board I had laying around that I put in to check the PSU. That's when I stopped and replaced everything.

 

[BriGuy]

Hmm... for what it's worth... I have a 500W Antec and it has two fans. The one on the back usually never runs. The one at the other side does, but not the one I can see from the back of the tower.

Are you sure the psu was bad?

 

[Jadzia]

Yes, it may yet be the graphics card. Since the psu pushes most of the the internal air out of the computer, many people will mistake a burning graphics card for a burning psu.

so I shut the computer off. At that point it seemed to be working OK.

Obviously, nothing had died a firey death at this point, so there's unlikely to have been cascading damage from one component to another. But the problem component may simply be failing at POST now, which is what seems to be happening.

Running the cpu with no heatsink could have caused damage to what may have been a perfectly healthy cpu. So that's a potential second problem.

 

[Marc]

Jadzia is correct. You never, ever run a desktop CPU without adequate cooling. A couple seconds is all it takes to make your multi-hundred-dollar chip into a paperweight. There is no guarantee it'll shut down fast enough to avoid damage.

And not even a good paperweight at that. CPUs aren't very heavy, after all. Several years ago, in the early days of the AthlonXP/P4 battle, Toms Hardware posted an article describing a test they ran to see what would happen if you ran a CPU without a fan. They started the computer, then removed the heatsink and fan. The P3 froze up. One of the Athlon CPUs burst into flames within seconds. The P4 had the first real heat protection circuitry and dramatically reduced it's clock speed to keep the temperature down. It slowed to a crawl, but kept running. Modern CPUs should do a little better than the P4. So, your CPU is probably okay, but still, you should never run it without heat protection. Even though it probably didn't melt down, you may have significantly shortened it's life expectancy.

yes that test carried out by Toms Hardware caused a bit of stink in a number of ways compounded by the site's very pro-Intel bias.

Can't remember when we first started to see fans and HSUs on processors but I think it was at the end the 486 era. First system I can member seeing heat sinks on the DEC Alpha - huge blocks of almunium.

 

[Jadzia]

yes that test carried out by Toms Hardware caused a bit of stink in a number of ways compounded by the site's very pro-Intel bias.

I've always had AMD chips (and cyrix in my first pc), but no intels.

I always seem to have had ati graphics too, although I don't specifically follow the brand.

Can't remember when we first started to see fans and HSUs on processors but I think it was at the end the 486 era. First system I can member seeing heat sinks on the DEC Alpha - huge blocks of almunium.

I think that's right. 486 processors usually had a low profile aluminium heat sink. Fans started being introduced in around 1995 with the introduction of ATX. Before then it was considered optional, but the ATX standard explicity stated that a cpu heatsink + 60mm fan must be fitted, in order to validate warranties, or something like that. I'm not sure where I read that now.

Since we're still with ATX, we still get standard issue cpu fans. Larger fans are not authorized in the standard, so manufacturers tend to play safe and not fit anything bigger, lest they be liable for cpu failures.

 

[Alpha_Geek]

Ice queen speaks true. Passive heat sinks were required with the early 486DX family, optional with the SX. When Pentium came along, as well as more compact chassis types, passive heat dissapation was no longer sufficient.

 

[Marc]

Since we're still with ATX, we still get standard issue cpu fans. Larger fans are not authorized in the standard, so manufacturers tend to play safe and not fit anything bigger, lest they be liable for cpu failures.

And it's interesting that we're still pretty much ATX. There was an attempt to introduce BTX (balanced technolodgy xtentions or something) which Intel was the main driver. The idea behind BTX was it supposedly more effecient at cooling and in a mini-tower case put the expansion slots at the top. Never took off as far as I can remember.

 

[Ar-Pharazon]

I tend to discount the video card as a problem, since when I tested (and probably finished off) the CPU in the older motherboard, I was able to visibly get into the BIOS settings, if only for a minute or two.

This video card has it's own fan, if that's helpful to the discussion. It's a big honkin' thing that only fits in the very bottom PCI-E slot. The RAM gets in the way if it's in either of the other slots.

The new mobo & CPU are being shipped from 2 locations, but I should have them both by Thursday. If the old CPU is shot, would there be any problem still trying it with the old mobo? As in, doing damage to that board. I don't intend to try it with the brand new one, just to be safe.

 

[Alpha_Geek]

Depending on how the old CPU failed, it could damage a new board if it shorted internally. Realistically, such a failure mode is unlikely, but Murphy dosen't seem to be favoring you lately. Don't futz with it. Just put the new stuff in and get going.

Don't forget the heat sink and heat sink compound!!!!

 

[Ar-Pharazon]

^ That's a 10-4 on the thermal goo and H/S. I just didn't think a couple minutes would be so bad, so my own fault on that step.

The heat-sync is massive and the fan that goes with it draws air straight in from the side holes in the left side cover. There's a tapered piece that goes right over the H/S fan, so it's like a wind tunnel effect.

I always have SpeedFan running, so I know where the temperature level is and it ramps up all the fans whenever necessary.

 

[Robert Maxwell]

^ That's a 10-4 on the thermal goo and H/S. I just didn't think a couple minutes would be so bad, so my own fault on that step.

The heat-sync is massive and the fan that goes with it draws air straight in from the side holes in the left side cover. There's a tapered piece that goes right over the H/S fan, so it's like a wind tunnel effect.

I always have SpeedFan running, so I know where the temperature level is and it ramps up all the fans whenever necessary.

Oh, yes, a couple minutes can be very bad. I burned up my first processor a long time ago. It was a Cyrix 6x86. The fan mounted on top of the heatsink (which was pretty massive itself) failed and I didn't even know it. Comp just froze up suddenly. Opened the case and noticed the fan wasn't moving anymore. Got a new fan, but the chip was toast.

 

[Ar-Pharazon]

The thing is, how does the Core2 Duo in my laptop not have the same kind of problem?

I don't remember any heat-syncs on it and only a small fan for cooling.

 

[Jadzia]

The mobile chips create much less heat.

Mobile Core 2 Duo P7xxx -- 25 Watts

Desktop Core 2 Quad Q7xxx -- 95 Watts

 

[Iasius]

Yeah, my P8400 has a TDP of 25W. Meaning that a heat dissipation of 25W should be enough in almost any situation. Desktop CPUs often go up to 100W or more during load. A Q6600 by comparison uses almost 20W idle and given the tiny area of CPUs (less than 1/2 sq in for a Q6600), that's an amazing power output. Most electrical cooking plates have a max power per unit of area quite a bit lower than even the idle power output of desktop CPUs!