My daughter's 3-year old Compaq Presario F700 had the black screen, no POST, reboot problem too. I tried all the RESET "techniques" I could find, and nothing worked. Most of the posts assumed that the black screen at least showed the BIOS POST, but this problem goes deeper than that. I located additional information (http://www.experts-exchange.com/Hardware/Laptops_Notebooks/PC_Laptops/Q_26270861.html) that indicates this is a problem with the Nvidia video chip getting so hot it melts its own solder and detaches from the motherboard. No video means the computer will not boot. So I tried the suggestions and they FIXED it.
Note: I cannot verify that this is the problem, but the fix worked; your results may vary.
First note, before you read the fix below, clean the lint and dust out of the holes for your laptop cooling fan(s) and heat sink, then test. If that fixes the problem, you're luckier than I was. I performed that preventative maintenance about three months before this problem arose. But BEFORE this problem comes up is the time to make sure your laptop can COOL itself properly.
I cannot find the youtube video that clued me in (search was done on another computer), but MANY thanks to the guy who demonstrated this technique. The details of the fix are this:
* disassemble down to the motherboard (link to disassembly instructions below)
* remove heatsink
* clean dust off of CPU, GPU, and related areas, also clean dust off of heat sink and heat sink fan
* clean off old heat sink COMPOUND from video, CPU, and other chips covered by heatsink
* trace motherboard on corrugated cardboard and cut out trace
* locate Nvidia video chip and its carrier on the traced cardboard
* cut-out square representing Nvidia chip and carrier
* wrap back of cardboard with aluminum foil (back means the side facing away from the mobo when the mobo is sitting atop the traced cardboard)
* cut-out square in aluminum foil for Nvidia (cut out and remove the foil cleanly, don't bend the foil into the hole or you'll CONDUCT heat onto the mobo and toast it)
* perfectly align cardboard mask with mobo
* flip mobo on its back, CPU and GPU down, with perfectly aligned mask on top (aluminum foil should be on top, protecting the cardboard and the mobo from heat everywhere except the Nvidia chip and carrier location)
* heat with heat lamp to bring mobo to 420 degrees Farenheit, and don't exceed 450 degrees F, this melts the solder without burning out the integrated circuits (see how hot are you getting the mobo, below)
* quickly, immediately after heating, flip mobo over and press straight down on HOT Nvidia chip with TOWEL, hold this position for 1 minute to let solder cool; Press straight down so that you don't slide the Nvidia chip out of place
* paint CPU, related chips and Nvidia chip with silver heat sink compound (use a business card or flat toothpick to smooth it into a thin layer)
* remove "rubber" pad from heatsink that used to cover the Nvidia chip
* place copper penny on heatsink compound on Nvidia chip to replace the rubber pad
* put silver heat sink compound on top of penny and spread around
* re-attach heat sink
* re-assemble and test (review disassembly instructions in reverse; be VERY careful when re-inserting ribbon cables that don't have zero insertion force sockets, or you may kink the cable and make it intermittent
The penny is thicker than the rubber pad, so the heat sink will press harder on the Nvidia chip than before. Also, pennies conduct heat BETTER than rubber pads. Use an old penny, if available, because they contain more real copper in their alloy. I'm not sure how long the penny will remain in place under real-world conditions that involve moving the laptop around, but the heat sink compound becomes like a glue after a few cycles of heating, so it might be stable for years; your results may vary.
Disassembly instructions here (http://www.insidemylaptop.com/disassemble-compaq-presario-f700-notebook/) reassembly is the opposite. :lol:
How do you know how hot you are getting the mobo? I used a heat lamp. I calibrated the distance and timing by performing test heating on a meat thermometer mounted to a 1x3 board at various distances and waiting until it reached hottest temperature equilibrium. For my 250W heat lamp bulb, I got the following readings:
5 inch --> 210 degrees F
5.125 inch --> 206 degrees F
5.5 inch --> 200 degrees F
5.75 inch --> 185 degrees F
5.875 inch --> 180 degrees F
I built a spreadsheet to plot these values and extrapolate to hit 420 degrees F using the fact that radiation falls off by inverse square law. My calculations suggested 3.6 inches for two minutes at 250W.
Target distance = sqrt (observed temperature / target temperature) * observed distance
Given my observations, the range of target distances varied a bit, but I aimed low so I could try again later if I didn't heat it enough. If I heated it too much, I'd fry the chips and the whole thing would be a lost cause.
Total Cost: $11.00 for tube of silver thermal compound, $6.00 for heat lamp bulb, and I already had a clamp-on light bulb socket to mount the heat lamp bulb in. Plus lots of time and patience.
For me, this procedure took about 3 hours to disassemble, about 1/2 hour to create cardboard heat mask, about 2 hours to calibrate distance and time, about 3 minutes to burn the mobo and press the chip back into place, about 10 minutes to replace heat sink compound and insert penny, and about 1 hour to reassemble. This stuff is not for the faint of heart. Static electricity is a MAJOR danger for your laptop when you disassemble it like this. And you might not get all of the disassembly/reassembly right, or your might break a component. I like to keep my skills up.
I doubt that I will ever buy another HP computer unless it comes with a 5-YEAR warranty. I've had more than one experience with a HP laptop having video concerns. I expect laptops to last a while, like more than five years. In all fairness, I'm typing this on a HP pavilion ze5200 from March 2003 that is still running.
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