I actually agree with the ''PC engineer''. Using 2 PSU on the same machine sounds like risky and bad practice. Also, I do not see how it would help for a overheating molex pin, that should signal a bad connection.

He liked the idea of being an "engineer" so he posed as one. Nothing new 😀
Better be who you are and write how you feel something should be done than do nothing, you can always learn it was not the best thing to do. Thats how experience is gathered.

Also a little unbalance with voltages wont do any harm. Today you have PSUs that are 2in1.

MaxWar wrote:

I actually agree with the ''PC engineer''. Using 2 PSU on the same machine sounds like risky and bad practice. Also, I do not see how it would help for a overheating molex pin, that should signal a bad connection.

Well I disagree, as long as you have a common ground link between the two PS units then all should be good to go.

I used to do this back in the Amiga days, has my own designed external PC PSU connected to my extranal SCSI Hard Drives and the Amiga was powered by its own PS unit.

Heh, about 10 years ago I knew a bloke who worked for a hospital and proudly proclaimed he was an 'installs engineer'. All he did was run Ghost to deploy disk images to PCs and then go deploy them. We used to get our rookie desktop support guys to do the same thing.

It's like how Microsoft had to change their MCSE cert from Systems Engineer to Solutions Expert. Turns out that real engineers, that studied mulitlple years for a degree, and pay yearly fees to be a member of a professional guild, took exception to computer janitors who studied for 6-12 months calling themselves engineers.

DonutKing wrote:

Heh, about 10 years ago I knew a bloke who worked for a hospital and proudly proclaimed he was an 'installs engineer'. All he did was run Ghost to deploy disk images to PCs and then go deploy them. We used to get our rookie desktop support guys to do the same thing.

It's like how Microsoft had to change their MCSE cert from Systems Engineer to Solutions Expert. Turns out that real engineers, that studied mulitlple years for a degree, and pay yearly fees to be a member of a professional guild, took exception to computer janitors who studied for 6-12 months calling themselves engineers.

Stojke wrote:

He liked the idea of being an "engineer" so he posed as one. Nothing new 😀
Better be who you are and write how you feel something should be done than do nothing, you can always learn it was not the best thing to do. Thats how experience is gathered.

That's sad. Identifying yourself with a false identity and being proud of it is not the best way to earn experience... Especially in case other people might suffer from your judgment. It's lying to both other people and yourself, in worst case - a psychiatric condition 🤣

Pretty bad how uninformed people can be these days let alone back then. Rigging a second psu to a semi modern system has been done in the past and there was a few guides how to do this but lost them. Thermaltake did at one time sold an secondary psu unit that mounted into the 5.25 bay that supplied only 12v and around a few hundred watts but they have been off the market for a long time. They only came in around the time of the 8800gtx was popular then vanished.

Perhaps I misjudged the guy, he seems to have engineered something...

Here's what you should be looking for:- c:\psu2.jpg Twin fan PSU […]
Show full quote

Here's what you should be looking for:-
c:\psu2.jpg
Twin fan PSU

In comparison, here's what you should AVOID:-
c:\psu1.jpg
Single fan PSU

Looks like he has managed to share his C: drive with the whole wide world!

BigBodZod wrote:

MaxWar wrote:

I actually agree with the ''PC engineer''. Using 2 PSU on the same machine sounds like risky and bad practice. Also, I do not see how it would help for a overheating molex pin, that should signal a bad connection.

Well I disagree, as long as you have a common ground link between the two PS units then all should be good to go.

I used to do this back in the Amiga days, has my own designed external PC PSU connected to my extranal SCSI Hard Drives and the Amiga was powered by its own PS unit.

I don't think is that safe. Keep in mind that you may be mixing not only GND but also +5 or +12v power lines, through the molex connector. I guess that connecting some hard disks to a PSU and the main board to another can be safe, but I don't know about that graphic card (or connecting two PSUs to the mainboard).

External SCSI drives have external power anyway, and SCSI drives are meant to be connected that way.

For internal IDE drives, to be safe, motherboard and all drives should be powered from same PSU, and all drives should be powered to be sure it works. It might not smoke up if one drive on cable is unpowered but it might not work either until it has power.

Even some motherboards smoke up if you connect only ATX PSU cable and not the extra power cables it needs, or connect multiple different extra power cables when only one is allowed.

For SATA drives, the SATA cable is only a point-to-point data link (and ground), so it does not matter if motherboard and each drive would have separate PSU, but of course the drives you want to use must have power when BIOS detects the drives, others could be left off.

For video cards, I have never even thought someone would want to power them up from another PSU than the one that is feeding the motherboard. I bet it could work with some motherboard and/or graphic card combinations, but nowhere it is mentioned they are specifically suitable or designed for this kind of usage. I would never do this unless manuals specifically say it is possible.

So being an engineer or not does not count here, it's both knowledge and experience that counts, but it can be expensive to learn if you fry a few motherboards or drives if you blindly connect stuff together.

Reminds me of the time I blew up a multi-I/O card in a 386 system, I forgot to unplug the joystick I was fixing while the PC was on. Fortunately the other parts survived, and I was really happy the joystick was not connected to a sound card.
I also blew up one brand new 3.5" floppy drive because I believed what the Internet said about which floppy signals are inputs and outputs. It turned out the Internet was wrong and two outputs were connected together and the floppy drive did not like it. So lesson learnt, just because someone says something on Internet, it is not necessarily correct or preferred.

Jepael wrote:

For SATA drives, the SATA cable is only a point-to-point data link (and ground), so it does not matter if motherboard and each drive would have separate PSU, but of course the drives you want to use must have power when BIOS detects the drives, others could be left off.

SATA is designed to be hot pluggable on AHCI machines. SCSI and other external buses are usually electrically isolated. The problem with using 2 separate power supplies is that it can cause some really funky ground loops, particularly when only one of the two power supplies is turned on (very possible with AT units). You can get current running to parts of the machine that aren't "turned on" (back feeding) which can cause trouble.

I would not have thought that it would be particularly important if a molex pin got hot.

Jepael wrote:

For video cards, I have never even thought someone would want to power them up from another PSU than the one that is feeding the motherboard. I bet it could work with some motherboard and/or graphic card combinations, but nowhere it is mentioned they are specifically suitable or designed for this kind of usage. I would never do this unless manuals specifically say it is possible.

Pretty much my thoughts. It might work fine on a specific PSUs/VGA/MB combo but that does not mean it works for all. Ultimately it would depend mostly on the design of the video card and the PSUs. If two power rails end up working together in parallel that would not be very good, some PSUs are designed to work with each other that way but as far as I know most PC PSUs are not. In any case I would be very careful If I was doing that kind of stuff.

MaxWar wrote:

I actually agree with the ''PC engineer''. Using 2 PSU on the same machine sounds like risky and bad practice. Also, I do not see how it would help for a overheating molex pin, that should signal a bad connection.

It's a common enough thing that they actually sell special adapters to allow for it. http://www.xoxide.com/add2psu-multiplepower-s … plyadapter.html

mr_bigmouth_502 wrote:

MaxWar wrote:

I actually agree with the ''PC engineer''. Using 2 PSU on the same machine sounds like risky and bad practice. Also, I do not see how it would help for a overheating molex pin, that should signal a bad connection.

It's a common enough thing that they actually sell special adapters to allow for it. http://www.xoxide.com/add2psu-multiplepower-s … plyadapter.html

I actually have such an adapter (mine is all wire though, which makes it easier to hide in a case) - came with a Cooler Master case a few years ago. It's simple enough to build one at home as well; the adapter is just connecting ps_on for multiple ATX connectors. I've used it for testing multiple PSUs at once, but honestly have never had a computer that's so power hungry a single PSU couldn't handle it (or that I couldn't buy an appropriately large PSU to handle it). There's also not many cases that will comfortably mount more than one PSU. IMO it's much neater to just get a larger PSU if that's what's needed.

On whether or not this is feasible:
I know a few years ago Guru3D did a review with 4 GTX 480s in one system, and it required two PSUs to start up (and that's the kind of system that's getting into the realm of understandable for needing more than 1 PSU), and nVidia has been shipping Quadro Plex for years, which runs a separate PSU just for those cards (perhaps more accurately, for the entire enclosure that houses them). It certainly is workable. Someone already mentioned the Thermaltake bay PSU; Asus also had a similar external brick that accompanied one of their cards (the dual 7800GT).

Here's the Guru3D review:
http://www.guru3d.com/articles_pages/geforce_ … i_review,1.html

Asus card:
http://www.tweaktown.com/reviews/834/asus_gef … zzle/index.html