7 replies to this topic

[s0nginmyheart]

Hi All, I have a Dell Dimension 4600 and I keep getting this black screen on startup that says "Previous fan failure" and something like press f1 to resume or f2 to run setup. I figured I would call Dell and order a new replacement fan but they harped about not having it in stock and whatnot. I'd like to know if I could go to a local store like Best Buy or Fry's and buy a replacement part, and if so, what should I be purchasing exactly (is there a specific model/type for the Dimension 4600)? Any help is most appreciated. Thanks---

[BranSys]

I have a Dell Dimension 4600i and received the same "Alert! Previous fan failure" message after I replaced the original Dell single fan cooling system with a two-fan system (92mm exhaust fan on the rear of the case and a CPU fan and heatsink combination). The original Dell design is very noisy as it employs a single 92mm fan mounted on the rear of the case which draws air through a green plastic shroud mounted over a large passive copper heatsink on the CPU. You can obtain a compatible 92mm rear mounted replacement fan on eBay (search for DELL DIMENSION 4600 FAN) but it will be just a noisy as the original. If you can put up with the noise, then this will be the simplest option. If you want to replace your existing cooling setup with a quieter one, these are the parts I fitted about a month ago and are working well (I have an Intel P4 3.00GHz Hyperthreading HT Socket 478 Prescott CPU - I am in the UK so prices are in GBP with approximation for USD): Xilence Red Wing 92mm Quiet Fan - 3&4 pin connection. Mfr: Xilence, Part #: XILENCE92 (4.73GBP/9.46USD - ebuyer.com) Akasa Intel Socket 478 P4 3.4GHz Extreme Edition Copper base Aluminium Fin Processor Cooler. Mfr: Akasa, Part #: AK-687A (9.99GBP/19.98USD - ebuyer.com) CPU Heatsink retention bracket SOCKET 478 (3.24GBP/6.48USD - ebay.co.uk) Terminal connector block (3-terminals) to connect the new CPU fan to the original Dell fan connector (0.99GBP/1.98USD - any DIY store) The websites are UK-based, but will give you detailed descriptions of the components even if you don't order from them. Unfortunately, Dell doesn't make life easy for you. You will need to replace the CPU heatsink retention bracket as the original will not be compatible with the new processor cooler. This will involve removing the motherboard, as the original CPU heatsink retention bracket is screwed into 4 risers which are, in turn, screwed into the backplate behind the motherboard. The risers need to be removed or the retaining pins for the replacement CPU heatsink retention bracket will not fit. You could avoid removing the motherboard and the 4 risers by drilling-out the 4 mounting points in the replacement CPU heatsink retention bracket and using the existing 4 retention bracket mounting screws. This would require some care as the retention bracket is made of a fairly flimsy plastic and could easily shatter. Be very careful when removing the original heatsink. You need to release the 2 green plastic retaining clips first. Then gently twist the heatsink clockwise/anticlockwise a couple of degrees first before carefully pulling it out. It will most probably be stuck to the top of the CPU by the thermal interface material between the top of the CPU and the bottom of the heatsink. This is best done when the CPU is warm - so run the machine for a few minutes before removal. Carefully clean the top of the CPU with pure isopropyl alcohol to remove the old interface material. The new heatsink usually has thermal interface material pre-applied. You will also discover that the 3-pin CPU fan header on the motherboard is not compatible with the 3-pin connector on the new CPU fan. You will need to cut the connectors off the original Dell fan and the new CPU heatsink fan and join the 3 wires of the new fan to the 3 wires of the original Dell fan connector with 3 terminals of a terminal connector block. The wires are connected thus: T1) White-Yellow(Tachometer); T2) Red-Red(+12V DC Power); T3) Black-Black(Ground). You can then plug the original Dell fan connector into the CPU fan header on the motherboard. You can solder the wires of the new CPU fan directly onto the pins of the original Dell fan connector plug by extracting the tiny pins from the plastic surround; but this is an extremely fiddly process in which you risk breaking the original connector. I found that simply cutting and splicing the wires together with a terminal connector block was far easier. You could also connect the CPU fan directly to a spare 4-pin molex power connector from the power supply unit via a 3-pin fan to 4-pin molex adapter and bypass the CPU fan header on the motherboard altogether. In this case, you will continue to receive the "Alert! Previous fan failure" message as the CPU fan's tachometer line will not be monitored. I found that with the Akasa CPU fan connected to the CPU fan header on the motherboard I was receiving an intermittent "Alert! Previous fan failure" message on boot. You may be lucky and not see this message. It would appear that the fan's tachometer is sending a signal that is regarded as just outside what the Dell motherboard regards as normal. The only way to ensure this message doesn't appear is to fit an official Dell replacement fan as I mentioned above. There are three ways to deal with this message. 1) Ignore it and press F1 to continue the boot process; 2) If you want to suppress the "Press F1 to continue. Press F2 to enter set up." message after the "Alert! Previous fan failure" message then press F2 to enter set up, scroll down and highlight "Report Keyboard Errors" and press the spacebar to change this setting from "Report" to "Do Not Report". After applying this change, the failure message will briefly appear and the boot will continue without any operator intervention required; 3) Ground the tachometer wire by connecting the White-Yellow(Tachometer) wires to the Black-Black(Ground) wires on the terminal connector block. This will disable CPU fan speed sensing so the system will no longer warn of a fan failure and no longer display the "Alert! Previous fan failure" message - this will now only appear if the fan connector becomes disconnected from the fan header on the motherboard. As the CPU fan is no longer being automatically monitored, it would be wise to carry out a regular manual inspection of the fan to ensure it is working properly. Grounding the tachometer wire has worked for my particular hardware setup, but is probably not generally recommended. In any event don't short circuit the Red-Red(+12V DC Power) terminal as this could destroy your system! Don't ignore the "Alert! Previous fan failure" message as this could eventually lead to an overheat of your CPU.

[Goldrush76]

Bransys (or anyone that can help), I have a similar problem with a Dell Dimension 470 workstation. I have recently upgraded the system to more than 8GB of RAM (9GB in fact) and a memory fan is required otherwise the system is halted during POST. There is no bios setting to change this behavior and the original dell part, WC417, ranges in price from $230-480. To say the least, I purchased a Corsair AirFlow Dominator, used wire cutters to chop down the proprietary Dell connector shape on the motherboard which I have seen and read so much about. Naturally, as everyone might imagine, the fan runs and I still get the error. I read your post... and one other post on the internet about this very system and error where another user jumped pins#1 and 3.... but neither you nor the other user gave any good details on how to do that. I am comfortable enough with making the modifications but I am not knowledgeable in actually wiring/rewiring electrical cabling of any type... so I don't want to mess up the process then break something else. What is the proper way, step by step, to short/ground the third pin/fan sensor on the Dell motherboard? I do *not* want to buy a 3pin-4pin adapter and use a lead of the main power supply... I'd still need to do another hack/workaround... no point. I'll just use what I've got. I just need to understand the electrical modifications since I have no experience in that area. I'm with doing it if I understand. Thanks.

[Doug]

I've asked for one of our Hardware specialists to have a look at your post and make a reply. Please be patient. We're all volunteers, but happy to assist. Doug

[appleoddity]

Because I don't have any experience wth this particular system I can't tell you for sure how it will respond to what you are trying to do. Just to clarify, are you getting the "previous fan failure" error message as stated in the original message of this thread? That problem has been known to be resolved by disabling the report keyboard errors option. This is a typical error message after using an aftermarket fan. The error will still briefly appear but it will no longer halt until you press F1. It will continue to boot normally. As you stated, and in my experience, Dell is extremely petty in their strive to make every single thing about a computer proprietary. This includes the fan connector on the motherboard. If it is like other systems that I have used an after market fan in, the standard 3/4 pin plug will not fit in the dell proprietary jack on the motherboard. You mentioned cutting, trimming the plastic. However, I have never seen a need to do that. Instead, you can make a note of the polarity of the plug (which way it plugs in), and then simply grab the plastic shroud around the pins with a pair of wire cutters and pull it right off. It is held in place by the pins and slides right off of the pins. This leaves the pins in place without any type of plastic shroud at all. This allows you to plug the standard connector on to the jack (now just pins) on the motherboard. As long as you paid attention to the polarity it will work just fine. As far as jumping out pin 3 to ground, I've never heard of doing that and I am curious if that actually works. It is a feedback line as far as I know and so grounding out should not hurt anything. There are certainly many way to accomplish this. However, I would test its effectiveness by simply taking a small wire and pushing it into the back of the fan plug (where the wires enter the plug) and jumping out the two pins (yellow, and black). See if it resolves your error message. If so, this is often so snug that you will not have to do anything further. However, if you want something more permanent you just need to get creative. I would probably cut the yellow tachometer wire where it exits the fan, trim it down to size, and then attach the free end of the wire to ground by stripping a small portion of insulation off of the black wire and soldering to it. I would then electrical tape the connection. Or, more likely I would use heat shrink tubing. To do so you can release the black wire from the plug by pressing the clip, slide on the heat shrink tubing, cover the connection and shrink it in place. Then you can reinsert the black wire into the plug. The fan can now be unplugged as one piece without having to disconnect, reconnect anything further. About as best as I can describe this procedure without pictures.

[Troy]

Possibly not the most helpful info, but I fixed a Dell in my shop the other week. It worked out faster and cheaper to replace the case, motherboard, and power supply with new standard form-factor ones (from reputable manufacturers, of course). I also had an old 775 CPU heatsink/fan that I cleaned up and used. This knocked out anything proprietary in the system (all of the parts I replaced were) and it's running like a charm. Also makes anything down the road a lot easier, and I had a happy customer.

[przemas]

About this one... if you have "previous fan failure" you should go to BIOS (F2) and go to the place where BIOS have tho logs of erros. Clean the log and save the settings. When you restart - it should work fine

[Duey]

hi,

when i was doing my 1yr IT apprenticeship, i worked on loads of those old compaq deskpro's and they had this sort of setup.

As far as jumping out pin 3 to ground, I've never heard of doing that and I am curious if that actually works.

all they did with CPU Fan was run a shortish cable from pin 1 to pin 3.

i know this image isn't the best but i've only got paint, the colours are probably wrong, and i'm not too good with drawing but i hope it helps all the same...

Attached Files

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