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System Power-On When PSU Switched On, No Display, No Beeps

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February 9, 2012 11:45:28 PM

Hi all, I’ve been battling with my HTPC for the last two nights, and for the first time in my building life I'm stumped! Hoping someone can help!

System:
AMD A8-3850 APU
Asrock A75-HVS
G-Skill Sniper 2x4gb
OCZ ModXstream 500W
Uses integrated video

Issue History
As I said before I'm using this system as an HTPC/Media "Server". Prior to being shutdown yesterday evening the machine was on for ~3 days non-stop with no issues. When I got home from work last night, I checked the temperatures and saw that the CPU was at 36C. Which is normal since the unit is shut inside a cabinet most of the time. Last week I upgraded the heatsink and exhaust fans to try and reduce the heat and noise. Prior to upgrading the HS and fans I had "under-voltaged" my CPU ~.1V and saw a significant drop in temp (~3C). I had read and article about a person able to drop .275 and decided to go for it! The system failed to boot, so I entered back into BIOS to up the CPU voltage, keyboard would not work. I restarted the system and tried again, same problem, keyboard would not function. Next step I took was to reset the CMOS, after that all hell broke loose.

After attempting to reset CMOS I was not getting any display, somewhere along the way my system also decided to power-up whenever I switched on the PSU (O to I), or plugged in with PSU switch in on position. I've since been able to stop the system from doing this by reseating CMOS without the VGA cable plugged in... Strange I KNOW!

What I've Tried
Reset CMOS multiple ways, battery and 2-pin header. Drained any residual power stored in caps by shorting power switch button.
Checked all PSU cables for proper voltage
Plugged in with the bare essentials (mobo,CPU,1 stick RAM (both slots, both sticks))
Tested with known good discrete video card
-Quadro FX, unsure of compatibility
-Was quite a sight to see a huge Quadro Gfx Card on a microATX mobo though!
No beeps with no RAM installed
Reseated CPU/Heatsink twice
-Noticed some thermal epoxy on pins, most likely from 1st reseat, cleaned the best I could
-No pins appear to be bent
-Both times the bond between HS and CPU seems to be "stickier" than normal, The one time it actually pulled the CPU from the "closed" socket

Who has anymore suggestions? Unfortunately I don’t have any compatible mobo/CPU fr swap.

Any help would be GREATLY APPRECIATED!! Thanks in advance!

Brad
February 10, 2012 12:01:33 AM

Probably your PSU. Thats where id start. If you are using a conductive thermal grease, AS for instance, and got it on the pins of the CPU, its in trouble.
February 10, 2012 12:11:00 AM

vrumor, Thanks for your post!

I checked the voltage at every (hot) pin, is that enough to rule out the PSU?

The thermal paste(AS5) I found on the CPU was on the board itself and could have shorted pins (unlikely), but given my luck. Although, the system was fine the last few weeks so I'm assuming the thermal paste must've got there the first time I reseated AFTER ths issue started happening.
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February 10, 2012 10:45:05 PM

Update:

I did order a mobo this morning.

Just put in a little more time..

Took out the CPU
- Visually inspected, found a little thermal paste on the tip of a pin.
- Cleaned up the pin and other spot with paste to ensure no continuity from the paste.

Inspect Mobo
- Visually inspected all components, nothing noticeable

I hope i haven’t damaged the CPU at all during this whole fiasco.. I wonder if the CPU could damage a new mobo at this point.. Considering ordering a new CPU at this point as well.
February 11, 2012 12:04:54 AM

Another Update:

I just looked up the Asrock beep codes and come to find out:



I guess including a beep code for RAM issue was too difficult, the hell with Asrock, what garbage.

Looking at this, maybe it is the CPU.. Well i ordered a AMD A3 8870K APU, i know it's overkill for an HTPC but it was 10$ more and no way was i was downgrading to an A6 (although its more than capable of what I'm doing). Some reviews say it idles a tab lower as well..

I'm just going to swap out both Mobo and CPU, less of a headache. Thanks everyone for the help! REPS!
!