Lack of Rear-Panel Audio in OEM Motherboards
For the other two people on the planet that have rescued HP, Dell, or other OEM motherboards from their stock cases, you might have noticed that the rear-panel audio jack on the motherboard stopped working. Apparently, some motherboards (an HP dC7100 CMT in my case) will turn off the rear-panel audio jack if the front-panel audio connector is disconnected. As it turns out, this is actually quite an easy fix.
According to Intel’s official front-panel connector specifications (see attached screenshot for a jumper layout), the motherboard uses pins 5, 6, 7,9 and 10 to detect whether or not the front-panel audio jack is connected to the system. To bypass the need for the front-panel connector, simply short pin 5 to pin 6 and pin 7 to pins 9 and 10 using some solder. After that, you should be solid.
–Adam
Hi Adam,
Thanx for the advice on the dc7100 audio trick. I also resued a dc7100 and have it in a new case, but I’m having problems with the front USB.
I connect it up, but I see the HP case front USB has 5 and 4 wires where as my case front USB has 4 and 4 wires.
Any idea how to fix this? I get the 918-Front USB Not Connected.
I’d appreciate it
John,
I’m currently at work, but I’ll take a look at my dc7100 motherboard later today and let you know.
–Adam
John,
According to Intel’s website (http://www.intel.com/support/motherboards/desktop/d850gb/sb/cs-013264.htm), the 5th pin (#10) is not used. I also have an Abit AN8-32x that has the same setup.
Perhaps you put the connectors on backwards? This occurs quite frequently. The ground (sometimes abbreviated GND, usually a black wire) should connect to pins 7 or 8. It’s also possible that you may have to short pin 10 to pin 8.
Let me know how it goes,
–Adam
John: The reason why it’s not working, it’s because for some reason, HP connected 1unused pin from Audio to 1 unused pin from USB. They both are soldered on the Front assembly making it grounded to the pc cassing through the little piece of metal they added to the front assembly
However, even if it’s not grounded to the cassing, it will work but the 2 pin need to be shorted together.
hope that help.
John, sorry, I should have added that although they don’t need to be connected to the casing, they ARE interconnected with other ground of the Audio and the USB assembly pin.
so the best way to emulate this is to connect thoses pin to the added metal plate of the front assembly.. They will be shorted and grounded with the other.
that will work.
Thanx for the help, I’ll try it out. I have been using it even though I still got the error message.
I’ll leave a update when I’ve tried it.
John, to do the correct modification, the best thing is to buy (or find) another USB connector and disasemble 2 wire without damaging the 2 metal end of each wire (4 in total). Then, use theses wire to connect 1 side to the motherboard on the USB connector (the right pin is the one below the blocked one (the one with a plastic cap)) this pin is unused on a normal USB connector.
Proceed the same with the audio connector. The right pin is again the one below the blocked one (with a plastic cap).
then, take the 2 end of theses wire and you’ll have to ground them on the front side pannel near the usb connector (I checked USB spec and there is ALWAYS a metal place on a front pannel to allow grounding USB) connect thoses wire end there.
To check if every is fine, you can take a cable tester and check if the other ground of the USB assembly on the front end is connected to theses 2 new wire. if it does, you got it.
picture are as followed:
The kind of wire you need:
http://adam-carter.com/wp-content/uploads/2010/11/SpareWire.png
you remove the plastic end, without damaging the metal end, to get a new skinned wire:
http://adam-carter.com/wp-content/uploads/2010/11/SkinnedWire.png
(you need 2 of theses wire, A and B (4ends))
you insert 1 end of wire A to USB end socket:
http://adam-carter.com/wp-content/uploads/2010/11/Usb_1.png
http://adam-carter.com/wp-content/uploads/2010/11/Usb_2.png
you insert 1 end of Wire B to Audio end socket:
http://adam-carter.com/wp-content/uploads/2010/11/Audio.png
you ground the other end of wire A and B to the Front assembly:
http://adam-carter.com/wp-content/uploads/2010/11/FrontAssembly.png
hope that help. took my like 3hours to figure it out.
regards
I have HP Compaq DC7700 sff and got the same error message:
918-Front USB Not Connected
Patrices solution worked properly.
Just grounded the mentioned Pin and the error message disappeared.
Thanks a lot.
empty
I’m glad you mentionned it. Although I didn’t made the wire test on the DC7700, it is logical to assume HP will continue to do the same fuzzy thing in the futur.
But for anyone testing my modification on another model, plz make sure first that theses pin are grounded on an original design before attempting my modification. Otherwise, it could result in motherboard damage.
By admited specification, theses pin are not supposed to be grounded. HP have their own “spec” though. It’s just a way to ensure that if something broke, you’ll be forced to buy HP component… clever, but not nice.
I’m not sure how long I’ll keep thoses files on my server, if someone want to hold my Image, you’re free to say it.
If you want me to clarify the design, I can do too.
just ask.
regards.
Patrice,
Thanks for the heads up before you removed the images. In order to ensure that your pictures can be accessed by future visitors, I’ve copied over all of your pictures to this website and modified the links in your post accordingly. Please let me know if you have any objections to my actions.
–Adam
no objection at all. I think it’s a great thing that this knowledge is preserved. I’m a computer tech and it took me some time to figure out this strange configuration. So it’s best to preserve that knowledge for futur user.
great web site by the way. Continue the good work.
Thanks for this post. Having to push F1 to get past USB and Front Audio errors was driving me insane.
There is great info above but after reading through it the conclusion can be summed up much more simply. HP uses a “sensor” pin to detect that front audio and usb are plugged in. In both cases its the pin that is by itself in the row of pins. It’s the pin that has a blank beside it. All you have to do is take that solo pin and short it out with a ground.
For USB I followed acarter’s advice and shorted pins 8 and 10 with a simple jumper. That fixed the audio error. I then cut and old HD led cable and jumped on end from the other usb ground pin (pin 7) and jumped it over to the “solo” pin on the audio portion. This fixed both my errors.
Thanks again this post was a lifesaver for me. Can’t really have a HTPC that you have to push F1 to restart.
TNX for Your fix.I grounded both PINs (AUDIO+USB) and it works fine. But still get error 512 – Chassis fan not connected. Is there any solution for this except to buy fan? On board there is 4 pins conector.
unfortunately Dusan, chassis fan ARE required on all HP motherboard. Beside, this particular motherboard tend to overheat a lot, I wouldn’t recommend running it without a chassis fan. (unless you keep your cover opened)
HP use a very hard to find 4 pin chassis fan but
Using a 3 pin fan will however work (without the RPM capability though) and will also remove the Bios prompt.
it worked on my DC 7600 and my DC 7700.
make sure your bios is up to date though (just in case)
Yes, I found that is necessary to connect extra fan to solve that. Then I connect one fan (3 pins) through the “fan mate” and set lowest speed, just to avoid BIOS F1 message. And now I agree with You.. That motherboard really need extra fan. When I install system i had open computer case and fan works really slow. But when i finished, i close box and suddenly i heard fan works werry fast and loud. Finaly i will probably connect some bigger fan to work at half speed.
TNX again.
one thing to mention, for some reason, some DC7700 (7600 as well) came with a aluminium heatsink with a copper center. And for some reason, some came out without the copper center.
Thoses without the copper center doesn’t cool down the cpu properly.
I suspect HP provided the one with copper center for all CORE 2 processor (wich are compatible with theses model) but theses motherboard can also come with lower cpu (Pentium D 3.2) and that’s when they come with regular heatsink. And theses doesn’T seem to cool down enough, even when you have the lower speed cpu.
hi, i was wondering what do you mean by ‘jumped the pins’.
can u please explain clearly how to fix the usb problem on my hp dc7600.
By “jump the pins” I mean to create a short using either a jumper, wire, or solder between two pins.
Unfortunately, I don’t have my old HP around any more so I don’t think that I can help you out with this one.
Brandon,
Look at my post early and check out the nice picture I took to explain in detail how to proceed with that modification.
How did you connect the 3pin fans into the 4pin outputs? Is there a pinout somewhere for that?
there is NO PINOUT in the service manual about this particular connector. Therefore, I had to take a guess.
I aligned 3 pin fan to the left. leaving 1 pin alone.
and the fan worked.
the 4th PIN seem to be used in SILENT mode where the fan can be completely stopped (hibernate mode for exemple)
with a 3pin fan configuration, your fan will never “stop” while your comp is running.
(Who’s using Hibernate mode anyway)
Thank you, that did the trick, no more “power supply fan not detected” at boot.
The remaining mystery is the CPU cooler, which after first 30 seconds goes to the full blast. According to lm-sensors neither of the CPU cores never go over 30C, but the fan still slowly accelerates to full speed. I’ve seen lots of “reseat the cooler” tips, but I think I’d be seeing pretty high CPU temperatures if the heat sink didn’t make proper contact.
I cleaned out the original paste and used silver when I first assembled the machine (I found the original machine parted out in a trashcan, the original case was damaged, so I just took the motherboard).
Well, here’s the kicker: I eventually pulled out the CPU fan only to notice that the machine does not require the CPU fan to actually work, only the PSU and case fans. So I took the extra case fan I had installed (to satisfy the BIOS) and installed it instead of the CPU fan. Problem solved. Had no cooling issues even with case closed, CPU at full speed and heavy load running.
one thing I noticed on this particular board.
The bottom of the heat sink have 3 similar side and 1 side wich is “over” elevated.
This particular side is adapted to fit condensator on 1 side of the motherboard.
If the heat sink is oriented on the wrong side, it will NOT be properly seated and 1 side of the CPU will take “AIR” instead of heatsink seating. Wich could cause a cooling issue and therefore cause a fan disruption.
sorry I’m out of cpu paste and I can’t dismount my heatsink to show you a picture.
My machine used to be a dc5750, and it has a heat sink that can’t be installed but in one way.
Hello. Just wanted to say a quick thanks to everyone that posted here. I recently put a HP dc7600 mother board into a generic case and had the same “918-Front USB & 917-Front audio not connected” errors. I couldnt figure out what was going on. Then I came across this page and I was able to resolve the errors.
“In both cases it’s the pin that has a blank beside it. All you have to do is take that solo pin and short it out with a ground”.
Nice concise directions, good pics to fully explain the procedure. Thanks 100 times!!!
Great discovery! Worked perfectly! Thanks!!!
The chassis fan connector on the motherboard does reguired a fan with at least 3 pins. 2 pin fan does actually work but you get a 512 error fan not connected.
Hello, I recently recased a dc7700 motherboard and would like to thank very much Patrice and all other contributors who helped in removing those error messages.
One difference, though, on the audio side. The front audio connector on the dc7700 doesn’t have the same exact pinout as previous models from HP. Front audio detetection is located on pin 4 instead of 7 so you have to short pin 2 (ground) to pin 4 to make the error disappear (see HP dc7700 technical reference guide for details : http://bizsupport2.austin.hp.com/bc/docs/support/SupportManual/c00771619/c00771619.pdf ).
Also, in my case, I replaced the original processor by a Pentium Dual Core T2200 and the presence of a chassis fan was getting unnecessary to me as those processors are known to be very energy efficient (only 23°C for both core in my case when idle). I was going for the “fan mate solution” before having the brilliant idea of shorting pin 3 from CPU fan to pin 3 from Chassis fan. And it worked! No more 512 error with only one fan connected and case is now really quiet, as it deserves to be. Only hoping this will not damage the board.
One last thought, the presence of a chassis fan does improve air flow, as my GPU was a bit cooler with the chassis fan connected (45°C vs 48°C without, for a GeForce 9300 GE). So, for those who have a recent C2D or Pentium Dual processor in their dc7700, removing chassin fan and shorting both fans pin 3 together can be taken in consideration, depending on your priorities (better air flow vs more silence).