Diagnosing A Used Samsung Laptop

aspen1135

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Mar 14, 2013
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Hello everyone! This is a long post but bare with me, its an interesting one.

I recently traded my old modded xbox 360 for a roughly 1 year old laptop without a charger on craigslist. Without having the charger, I knew there was a high probability it could not work. I ordered the charger and when it arrived and surprise surprise, the laptop wouldn't power on. I am not upset about taking the deal because the xbox value was around $100-150 and I never used it anymore while the laptop (if it worked) was around $500-700 so I was still getting the better end of the deal.

Now that I have that cleared up the laptops history, on to diagnosing the laptop.. The laptop is a Samsung NP300E5C. The hardware is decent; rocks an i5 and this particular one was recently upgraded to 8gb of ram. When plugged in, the charging LED's light up, and when you press the power button (sometimes takes a few times) the power LED will light up blue like its about to boot but it will not post. The fans do not spin, and the LCD screen does not turn on and all this led me to believe it was a faulty motherboard. However, the green BIOS battery was detached at one point and was given to me separately at the time of the exchange. I am unsure whether this effects the booting process or not.

When I (tried) opening the case, the screws were so damn tight that a 2 of them had to have the heads drilled off in order to open the case. When I got a look at the motherboard, I inspected the hardware and cables for anything loose or damaged. Everything seemed to be in order. I took off the CPU heatsink and ran into the first problem. Unsurprising, there was a VERY messy thermal pasting job on the CPU. Manufacturers are notorious for not doing a good thermal pasting job but this one was so bad it made me cringe, and I knew it had to have been done by someone else at one point. I cleaned the old thermal paste off with alcohol swabs and applied a thin new clean coating of arctic silver on the chip. However, the damage may have already been done.. There was some transparent paste-looking residue on the green part of the CPU right underneath the silver chip. Regardless, I assembled the computer again and tried it but nothing changed during the attempted boot.

The bios battery's cable attachment plugs into the underside of the motherboard I think, which is only accessible by unseating the whole motherboard out of its case. Whoever worked on this laptop last had to have used a power drill, because the screws are so tight that I probably have to drill the heads off which puts the motherboard at risk of getting damaged. IF the CPU is damaged and its causing the laptop not to boot, I do not want to risk damaging the motherboard unless its needed.

I looked online and motherboards go for about $130-150 while the CPU, if I got lucky, I could replace for $80-120 new/used.

So my question for you guys is, would replacing the CPU fix the booting issue or do you think the motherboard is the culprit? And what about the BIOS battery? I am doubtful that the battery is the cause of the booting issue.
 

aspen1135

Honorable
Mar 14, 2013
2
0
10,510
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Update: The computer turns on and the power stays on. The button needs to be re-enforced from the backside for it to register. The fans spin up after a bit of time at boot but I can't get a display from either the LCD or the HDMI port. I got the motherboard flipped over and took a look but nothing looks too unusual. I'm beginning to think its a bad GPU which means the motherboard still needs to be replaced. I'm pretty sure the computer wouldn't boot at all with a bad CPU. I can test this theory by trying to boot the computer without the CPU in completely but I'm reluctant to.
 
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