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General Septem

That was a pretty lightshow

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So some of you saw my last thread where my rig wouldn't boot up with my 7950GT in it. The PSU actually wouldn't supply power to the rig, even trying both PCIe connectors and even trying it once without the connector. That card got RMAd for a replacement.

 

Just to recap, that card actually did boot until I replaced the stock cooler with the Thermalright HR-03. I don't know why it did not boot after I installed it but something must have happened.

 

Apparently the card they sent back was jealous of the last card. I very carefully installed the Thermalright HR-03, foregoing the initial test with the stock cooling first. However I was extremely careful this time and am 100% positive that nothing I did caused anything to short out. I even placed a plastic bag over the fins to prevent them from coming into contact with the back of the card as I was installing it.

 

So I booted up. It got past the POST screen and up to the point where it backs up the CMOS.

The system cuts power.

I press the power button again.

Two seconds elapse. Then I hear a popping sound. I look over and see an orange flickering light reflected against the wall from behind the video card, accompanied by rising smoke. I quickly get out of my seat and look over the card to see a nice little plume of fire coming from my brand new 7950GT. Actual real fire. Kind of looked like that time I taped 20 candles together and lit them all at once, for any of you who've seen my birthday video.

 

So I flicked off the power supply switch, and the fire stopped. I let it cool off, and in the mean time prayed my entire rig wasn't destroyed.

 

Well obviously it wasn't, because I'm here on the forum.

 

Looked to me like it was a MOSFET that caught fire. It was right near the power connector at the upper right corner:

 

th_IMG_1773.jpg

 

So I put the old card back in, took the HR-03 off the 7950 and put its stock cooling back on, and put in for an RMA from newegg - this time for a refund.

 

But damn. Two bollocksed cards in a row? Do you think it could be something wrong with the PSU? Could it possibly be the HR-03? Could it be the alcohol wipe I used to clean the GPU?

 

I actually took a video of myself installing the HR-03 which I originally planed to upload to youtube, if that would be at all useful although I doubt it.

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My guess is that the PSU is overloading the PCIe 12V connector and frying the GFX cards (especially since this is the 2nd ruined card).

 

Or maybe it was a bad batch of mosfets (remember Dell's laptop battery fires).

 

I doubt that the cooler was responsible; even if the fan had been disabled in the BIOS, the GPU would just run a bit hot until the fan was enabled W/ a BIOS flash.

 

Interesting experience; would have been cool to see a vid of the fire.

 

Good luck w/ the RMA; hope you'll ge a card that works and fin out what killed the cards

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The HR-03 is actually a passive cooler, so there is no fan. You can install one but it won't fit under the CPU cooler and I've sinced used the 90mm fan I bought for it for something more important.

 

My thought regarding the cooler was that either something was preventing it from making contact with the GPU (why a MOSFET in the complete opposite side of the card though?) or something was shorting out.

 

My other thought was that maybe there's something in the alcohol preps I used to clean the GPU that destroys electronics. Now that I think of it I've had to replace two headphones after I tried to clean them, but I don't know if that's because of the alcohol or if it's just because they got wet or just decided to stop working.

 

I'm thinking what you are, though, that there's something wrong with the PCIe connector. And if there's something wrong with the PCIe connector I'm probably damn lucky to still have a rig. :eek:

 

We're going to check it with a DMM and find out for sure, though. If that's the case, I probably used the right one when I first booted the first card up, and then fried the card after I installed the HR-03 by plugging the bad one in. Then since it was already dead, changing the plug out didn't help, nor did trying to run it without power.

 

Haha, you're the second person to say a viddy of the fire would've been cool. It was just a little flame, really wasn't all that exciting. ;)

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The HR-03 is actually a passive cooler, so there is no fan. You can install one but it won't fit under tha CPU cooler and I've sinced used the 90mm fan I bought for it for something more important.

 

My thought regarding the cooler was that either something was preventing it from making contact with the GPU (why a MOSFET in the complete opposite side of the card though?) or something was shorting out.

 

Sorry, I didn't realize that the HR-03 is passive. Even if there were no cooler installed; I think the worst that could happen is that the GPU overheats, reaches the thermal threshold (set in the BIOS), and shuts off. In such a case, the GFX card would stull work if properly cooled.

 

 

My other thought was that maybe there's something in the alcohol preps I used to clean the GPU that destroys electronics. Now that I think of it I've had to replace two headphones after I tried to clean them, but I don't know if that's because of the alcohol or if it's just because they got wet or just decided to stop working.

 

There might be some acid in them that could "eat" traces but I doubt it; since I'm assuming that they're like the ones that are in a first aid kit, and such acids wouldn't be good for open wounds.

 

 

I'm thinking what you are, though, that there's something wrong with the PCIe connector. And if there's something wrong with the PCIe connector I'm probably damn lucky to still have a rig. :eek:

 

We're going to check it with a DMM and find out for sure, though. If that's the case, I probably used the right one when I first booted the first card up, and then fried the card after I installed the HR-03 by plugging the bad one in. Then since it was already dead, changing the plug out didn't help, nor did trying to run it without power.

 

LMK what you find out about the PSU. I'd say that if for some reason it is frying the PCIe GFX cards, then it would be prudent to replace the PSU.

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Sorry, I didn't realize that the HR-03 is passive. Even if there were no cooler installed; I think the worst that could happen is that the GPU overheats, reaches the thermal threshold (set in the BIOS), and shuts off. In such a case, the GFX card would stull work if properly cooled.

 

Would that be in the card's BIOS or the system BIOS? I actually have the shutdown temperature disabled.

 

LMK what you find out about the PSU. I'd say that if for some reason it is frying the PCIe GFX cards, then it would be prudent to replace the PSU.

 

What exactly should I look for when I'm testing it? Thanks for the responses by the way. :D

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Would that be in the card's BIOS or the system BIOS? I actually have the shutdown temperature disabled.

 

The thermal threshold I was referring to is set in the GFX card's BIOS (usually set @ 125C); does the same as the CPU shutdown temp, just for the GPU

 

 

What exactly should I look for when I'm testing it? Thanks for the responses by the way. :D

 

Most likely would be a current overload; i.e. driving that 12V rail at full power, rather than adjusting for the current requirements of the loads connected to that rail. Another possibility woud be that the PSU is supplying a mugh higher voltage to that connector or perhaps it could be reversed polarity on the connector.

 

IMO it would be wise to just replace the PSU; rather than risk going 3-0 on fried cards or kill more than just a GFX card.

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Most likely would be a current overload; i.e. driving that 12V rail at full power, rather than adjusting for the current requirements of the loads connected to that rail. Another possibility woud be that the PSU is supplying a mugh higher voltage to that connector or perhaps it could be reversed polarity on the connector.

 

So the PSU voltage is supposed to adjust depending on the card, or are you talking about amps?

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So the PSU voltage is supposed to adjust depending on the card, or are you talking about amps?

 

Should be constant 12VDC variable current (based upon requirements of the card). If either the voltage or the current is too high then it is overloading the card. If the card needs 14A @12V and the PSU is providing 20A @12V then it is overdriving the power, or if the output is say 24V then it's a voltage overload

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Should be constant 12VDC variable current (based upon requirements of the card). If either the voltage or the current is too high then it is overloading the card. If the card needs 14A @12V and the PSU is providing 20A @12V then it is overdriving the power, or if the output is say 24V then it's a voltage overload

 

I didn't think amps could be "driven", I thought the device just drew what it needs (I'm not questioning, I'm just wondering). How would I check for that then?

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Amps are shoved through at a given voltage.

 

I'll try and relate it to water.... You can have 100 PSI but only move 1 gallon per hour... thats like 100 volts and 1 amp. Conversly, you can have 1 PSI, but move 100 gallons per hour... thats like 1 volt and 100 amps.

 

Basically, voltage is the "force" pushing amps (coulombs per second, in short, its an amount of electrons moving past a given point at a certain time) through a wire/conductor/semiconductor.

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Amps are shoved through at a given voltage.

 

I'll try and relate it to water.... You can have 100 PSI but only move 1 gallon per hour... thats like 100 volts and 1 amp. Conversly, you can have 1 PSI, but move 100 gallons per hour... thats like 1 volt and 100 amps.

 

Basically, voltage is the "force" pushing amps (coulombs per second, in short, its an amount of electrons moving past a given point at a certain time) through a wire/conductor/semiconductor.

 

I understand that much but I didn't think more amps could be driven through an electronic device than what was being drawn by it. Kind of like a faucet only draws as much water flow as it's turned on to. I don't know anything about electronics though (I'm going to take a course in January hopefully) so I could be wrong.

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Power supplies always drive the power supplied to the load; and can operate either at constant voltage, variable current; constant current, where the voltage fluctuates within a given range; or constant current, constant voltage (Constant power).

The root of the matter is that the voltage is the carrier for the current.

Computer PSUs operate at constant voltage and variable current; i.e. for a given voltage (potential) it adjusts the current based upon the load resistance (V=IR) up to the current limit determined by the max power per rail (P=VI).

On the other hand, there are power supplies that don't care what the load resistance; they just provide a certain current @ a given voltage (P=constant). If this is the case, it can overdrive the load.

An underpowered PSU is the case where it cannot provide the current desired by the load.

 

Moral is; the PSU drives the load, which takes whatever power it is given. Think of it as a car; your are the driver (PSU) and the engine/drivetrain is the load (i.e. GFX card) the engine only gets the fuel (power) you provide it (w/ the accelerator). Think of the engine RPMs as current; if you have it in neutral (R~=0) the more fuel you provide, the higher the RPMs, get them past the red-line and you start overdriving the engine, which can cause it to fail.

In this example, the Computer PSU would act like you watching the tachometer and adjusting the fuel flow to keep the current W/in a safe range.

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