Dell Optiplex 760 MT - PCIe card sometimes not detected by BIOS on hard boot

[cpams322]

About a month ago I bought two Dell Optiplex 760 MTs on ebay. Both systems are exactly the same in EVERY way. I updated the BIOS on both to A16, both are running Win 7 Pro 64 bit, both have the same amount of memory (6gb DDR2 PC6400 Nanya brand RAM). Both have the same updated drivers and other updates from Windows and from dell. Both run great - except for one problem.

Last week, I bought a Dodocool 2-port USB 3.0 PCIe x1 expansion card from ebay and it works on both Optiplex 760 PCs when placed in either the PCIe x1 or x16 slots. Both PCs have the latest Renesas driver installed for that card. So what's the problem?
Well...

on only one of the systems, it's a hit or miss as to whether the BIOS detects the card at startup (the BIOS detects all the PCIe slots, just sometimes not this particular card - it will just show "empty", when it should say "USB").

Therefore, if the BIOS doesn't detect the card, then it's not available in Windows when Windows loads in. Therefore, when I start the PC, I always have to enter the BIOS to see if the card is detected. If it is, fine, I just exit the BIOS and let the PC boot into Windows and all is fine. But if the BIOS doesn't detect the card, I exit the BIOS, push the power button on the tower to shut the system off, then power on again and usually the card is recognized (sometimes might take 2 tries, but usually only one). I have tried flashing the BIOS 3 times and that didn't fix the problem.

It never happens if I simply do a restart from the OS. On a restart, the BIOS always remembers/sees/detects the card. It only happens if I do a shutdown and have to power-up the system using the power button on the tower.

This problem happens only with this one system and only with this particular PCIe card and not any others and it doesn't matter if it is installed in the PCI x1 or PCI x16 slot - the problem is the same. No problems on either slot with any other PCIe cards.

I have tried many, many, many times to replicate this problem on the other identical PC but I cannot replicate it. It only happens on ONLY the one identical system and ONLY with this specific PCIe card.

I'm at a loss as to what the problem could be. At first I thought it was a defective motherboard or defective PCIe x1 slot but when I saw that it also happens on the PCIe x16 slot and all other PCIe cards I've tried have no problem, I don't think I can conclude it is a bad mobo or slot(s).

I also don't see how it is a defective PCIe card since it works flawlessly on one system. IN fact, it works on both systems, just that in one the BIOS might not detect it.

I have searched and searched for a solution or even just an explanation of some sort for about a week with no luck.

I'm hoping someone here can shed some light as I have come to the point where the only solution I have left is to bash my head against a wall!

Both systems:
Dell Optiplex 760 MT
Nanya 6GB DDR2 PC2-6400 (800MHz) RAM
Intel Core 2 Duo 3.0GHz E8400 Wolfdale CPU
Dell Inc. 0M858N mobo
SLIC v2.1
SMBIOS v2.5
BIOS vA16
Windows 7 Pro 64-bit SP1
(using on-board GPU)

 

[TMTOWTSAC]

Shot in the dark here, but can you check to see if the CMOS battery in the first machine is dead?

 

[cpams322]

OK, even though the old battery was still good, measuring a little over 3v, I replaced it anyhow.
Brand new battery is measuring 3.23v. Problem still persists.

I also cleared/reset the CMOS. Still have the problem. 🙁

 

[TMTOWTSAC]

I guess it's unlikely to be a power issue then, but if you think it's worth the hassle you could also try swapping the PSU's between the machines. I'm not holding out a lot of hope though. Intermittent problems like this are one of the hardest to pin down.

 

[cpams322]

That's the one thing I haven't done yet. However, I just check the voltages on all the wires on the power connectors of both PSUs under load and both are identical (and correct).

The only difference is that on the "good" PC gray (Power_OK) voltage is at 4.85v when powered-on and on the "problem" PC it is 4.7v. However, this should not be a problem because I believe the voltage on this wire is not set in stone. It's just supposed to be between 3 to 5 volts being the most ideal range. If I'm wrong, please let me know.

Because of this, I really don't think the PSU is the problem and I'm not sure I'll be switching the power supplies just yet. But I might change my mind later.

I'm about half tempted to order another USB card just to see if the problem is the same. Not sure I'm going to do it, though.

I'm still open for suggestions.

 

[cpams322]

Well, I just did a bit of surgery on my PCIe x1 slot. I figured, maybe the PCIe slot's pins are not making as good of a contact as the other identical PC's pins are, so I very carefully bent each pin VERY SLIGHTLY inward so they would make better contact with the card's contacts.

I don't recommend that most people do this! I came very close to making a permanent mistake 4 times. It's a very delicate procedure and one mess-up could render the slot useless and even possibly kill your motherboard with a short (and even kill other components).

First I only did the pins on one side of the slot, and that didn't make any difference.

Then I finished by doing the pins on the other side of the slot...and
no difference!

This particular PC simply does not want to regularly detect that specific PCIe card!!!

I have posted this problem on 3 forums, including Dell's forum (yeah, I finally got in!), and this is the only forum thus far that has given me any good suggestions on this matter. Thus far, I have not received any responses on Dell's forum. lol

If anyone has anymore suggestions, I am definitely open to them as I will forever be up to solving this issue. But until someone else chimes in with some info/fixes/suggestions, I will have to lay this to rest for the time being. I have lost a lot of time on this problem.

I feel that there probably is a solution, but my knowledge of PCs isn't extensive enough to know of it.

For the time being, I feel defeated. 🙁

 

[dontlistentome]

I think I'm missing something here. If this only happens with this particular computer with this particular card, and you have two identical computers with two different cards, why don't you just switch cards?

 

[cpams322]

Only one card.

 

[cpams322]

Well, problem is solved, thanks to TMTOWTSAC.

I guess it's unlikely to be a power issue then, but if you think it's worth the hassle you could also try swapping the PSU's between the machines. I'm not holding out a lot of hope though. Intermittent problems like this are one of the hardest to pin down.

I was wrong to just test the output voltages on each PSU and not switch them out. The problem is in fact the PSU.

This morning I decided to take a look at the spec sticker on each PSU and, lo and behold, they are not identical. THey look identical but each has a different part #.

- The part # on the problem PC's PSU is P192M, model # L305P-03.
- The part # on the "good" PC's PSU is 0MK9GY. model # H305P-02.

All the specs on the stickers are identical expect for the input specs.

- On the problem PC (PSU P192M), the input says 100-240V~/5.6A (50-60Hz) (which is the same as many of the "Bronze" aftermarket PSUs I have been looking at recently online)
- On the "good" PC (PSU 0MK9GY), the input says 100-240V~/4.7A (47-63Hz).

I'm not sure if these specs are what make the difference, I'm just pointing out the differences in the specs on the stickers. It very well could be that the input specs mean nothing and that the P192M is starting to fail, but I have had no other problem than the intermittent detection of this USB card using the P192M PSU. The PC with the P192M was manufactured about 8 months before the PC with the 0MK9GY PSU, so it could be that Dell replaced it due to this defect I am seeing.

So now, the P192M PSU is in the other PC (the "good" one) and now that PC is suffering the same problem - intermittent detection of this one PCIe card in either PCIe x1 or x16 slots.

And now, the "problem" PSU has the 0MK9GY PSU in it and it is no longer the "problem" PC, it is now the "good' PC. Detection of the PCIe card in either x1 or x16 slot is always detected...ALWAYS!

SO the formerly "good" PC is now the problem PC and the former problem PC is now the "good" PC, all because of switching the PSUs!

Thanks, TMTOWTSAC, for suggesting swapping out the PSUs. And I am sorry I decided not to take your suggestion to heart and instead just test the PSU output voltages. Just goes to show you that testing output voltages, even under load, is not a 100% indicator of a faulty or "problem" PSU!