Resolved Confused By 12V Power-supply Requirements

Hi, I hope someone here can explain or sort this out for me.
Rebuilding a AMD System.
Motherboard is Gigabyte GA-MA790X-UD4P, It has 24 pin ATX and 2 x 4pin 12V.
My PSU is OCZ 500W 6 month old, it has 24 pin ATX plus 1 x 4pin 12 V.
In the PSU specs it states that it has: +12V1 - +12V2 - and -12V.
The Manual of the Motherboard is confusing me:
ATX_12V_2X4/ATX (2x4 12V Power Connector and 2x12 Main Power Connector.

It states: The power connectors are compatible with power supplies 2x2 12V and 2x10 power connectors.

Any clarification would be greatly appreciated.
hawk22

 

On the Gigabyte site it clearly states that it has a 24 pin connector plus an 8 pin 12V connector. You need a power supply that has the extra 8pin 12V connector

 

I built a Gigabyte system a few months ago and was concerned about the 8 pin (2 X 4 pin) connector. I was told it only needed one 4 pin connector. It worked and has been running fine. You probably only need the extra 4 pin connector if you are running top-end CPU, memory, etc.

Just check if there are minimum requirements for the Amperage on the 12 volt rail. If you are putting in an add-in graphics adapter, check if the adapter's manual states minimum or recommended power requirements.

I found you don't need the "extra" 4 pin connector.

Matt

 

Thanks Matt, I did some googling with people stating like you, that they have only been using 1 x 4 pin.

markmadras, one thing that I can not work out is my PSU states as I mentioned
+12V1 and +12V2 meaning to me it has two 12V rails, but only 1x 4pin 12V.

 

From what I have been reading this motherboard is non standard but power supplies are available with the 24 pin and 8 pin connections. Unless you take a chance and follow what Mattman has said your only other option here is to get more details from Gigabyte to confirm if you can use the 4 pin connector in the 8 pin socket.

The 2 x 12V rails will be distributed amongst the various connectors. I guess one rail may just be for the 4 pin connector.

 

Hi Mark,

Something I am going by is this

I could not find similar information when I was building the system I did, so I asked the supplier of the Gigabyte system where I purchased it. I used their suggestion and found it worked.

Gigabyte don't seem to have very clear instructions (which I have across for more than a decade).

Hawk, ask the motherboard supplier.

Mark. I am only reporting my findings. If the system requires extra power connections, my experience (after checking), was that they were not needed.

Matt

 

Hi and thanks Matt and Mark, I will have a go and see what happens with just the 1x4 pin.
Mark, in the Motherboard Manual it does not refer to it as a 8 pin it is indicated as ATX_12V_2 x 4 pin.

 

OK, they really should supply better instructions with motherboards. Like Mattman I am only reporting what information I can find myself.

On the Gigabyte site the connector was just listed as 8 pin and it could be that in the manual they list it as 2 x 4 pin just to make it clear that it has 2 rows of 4 pins, this is unlikely to be an indication that it will take 2 four pin plugs.

You will probably find that it all works by using the 4 pin connector, but does it fit and will it fit in more than one position, if so, which do you use? I would not want to say its OK to use the 4 pin connector unless I had some hard facts infront of me. My advise would be to contact the supplier or the manufacturer.

Let us know how you get on and please report back your findings so we can use this for future reference.

 

Expanding this issue a little bit further, I have contacted the previous owner of this board, and he feels very strongly about using 8 pin suggested at Benchmark Reviews, and according to Marks research, opposed to the Gigabyte Manual of 2x4 pin.
Anyhow I was wondering what you guys think of the idea of using an adapter, I have ordered an 4 pin Molex to 4 pin square power adapter.
I don't know how this would work, but I have previously successfully used a 2 x molex to 1x 6 pin PCI-e Video adapter.
hawk22

 

I think you would be best to check with the manufacturer or follow the advise of the boards previous owner.

As I mentioned earlier where the Gigabyte manual says 4 x 2 pin I am quite sure this does not mean that two 4 pin plugs are needed, it means that the connector has 2 rows of 4 pins and an 8 pin plug is needed. Obviously, as Mattman has said, you may be able to use one 2x2 4 pin connector and the mobo will power up, is it obvious which pins it will go into?

Using an adapter to go from the 4 pin molex to a 2x2 square plug may do the trick but you best be sure that it has sufficient amperage available to run the CPU. Several sites I looked on mentioned at least 700W for this mobo but I guess that depends what you have connected to it and the size of the cpu, may be worth checking with the seller what PSU he used.

You might be lucky and find your method is going to work, but it may simply not function.

The correct power supply with an 8 pin 12V connector would be ideal, or if you could get a 4 pin molex to 8 pin adapter then that might be OK.

At the end of the day I am sure your best approach would be to contact the manufacturer and then you will no for sure what you can and cannot do. I would also check up on the power supply wattage.

 

Have you looked closely at the 4 pin connections? One is keyed as the standard (square) 4 pin, the other is keyed differently. Would the adapter be keyed correctly?

You might want to check some information and specifications of newer PSUs and see if you can find out some details about the extra connector.

I tried asking a question at the Gigabyte website many years ago and never received an answer, so let me know how you get on if you try. The technical information at the Gigabyte website (or in the manuals) doesn't seem to be written with a strong English language background.

The motherboard has Crossfire and a lot of extras, so it is more than just "standard ". Unless you were just using a basic level of parts (CPU, memory, graphics, etc), I would investigate thoroughly. I was making quite a basic machine, it was just for word processing, net surfing, etc, so the power requirements were not high.

Matt

 

Well I am waiting now for an answer from Gigabyte.

 

I just had another look at this problem and found the online manual. Having now read the instructions and seen a picture of the connector I can safely say that the 2x2 12V connector will do the job. Due to the plastic moulding around the pins it is not possible to put the connector in the wrong place. The mobo, when new, is supplied with a safety cover over the extra pins that only get used with an 8 pin connector.

I am quite happy to tell you to go ahead and plug it in. The 2x2 plug will only fit on pins 3 4 7 8. The manual does list all the pin outs and shows 1 2 5 6 are for 8 pin connector only. The 4 pin square adaptor you have ordered will do the job but you could just check that the +12V is on the correct pins as per the manual.

You will note, as stated in the manual, that a minimum power supply of 500W is recommended which you have, but if high end peripherals are going to be used you should consider getting a higher wattage PSU preferably with the 8 pin 12V connector.

It is odd that the manual does not seem to explain what benefit, if any, there is in using an 8 pin connector so I can only assume it is completely optional. That being said I did not read the entire manual so may be it is explained elsewhere.

 

Hi there Mark, Thank you so much, for taking all that time to look into this situation. This is how I sort of thought it would be, but googling around had given many different opinions. At the moment I will only be using a AMD Athlon II X2 240 2.8GHz and 4 Gig of G.Skill Ram and a single 1 GIG Video Card.
Further down the track I will be looking at a Phenom II X4 955 CPU, and I am fully aware that I will then have upgrade the PSU to around 750W.
And no Mark I did read fully through the Manual hoping to find some reference to the 8 pin connector but nothing.
All in all I have not been able to find much information on what they call
EPS /ATX 12 V 8 -4 pin x 1.

I have today registered with the Gigabyte Forum at tweaktown.com to see if I can get some explanation from Gigabyte.

In the meantime I will continue working on setting up this machine.
hawk22

 

OK hawk22, it does seem that the manual for the board is missing some information, obviously those extra 12V connections serve some additional purpose and I can only guess it is for the top end CPU's or top end peripherals. I am sure your current PSU will be fine with the set up you presently intend to use.

Meanwhile it will be interesting to hear what comes back from the Gigabyte forum.

 

Just to update, I have received a reply on the Gigabyte Forum, by a senior Gigabyte member and he did confirm your and Matt's answer, he also claims to have run his machine with the same setup stable with no problems, only upgraded the PSU when he overclocked the system.
Now I do feel better, naturally I have not heard from Gigabyte Support.
cheers
hawk22

 

Yup, that's typical, a forum reply from a volunteer came before one from a paid member of staff.

That's good, so you can now confidently set up your new system.

I think that resolves this thread.

It will be interesting to hear the reply from Gigabyte (when it arrives) which I am sure will further confirm what you already know, but may include some usefull information on those spare 12V connections.

 

As a FYI, I chose a Phenom II X3, I think I would have upgraded the power supply for an X4. The original 4 pin connector was for "extra power for the CPU ". so I expect (expected) the extra 4 pin power is for the CPU.

I wonder if Gigabyte get a lot of questions like this? I know when I select a motherboard, the general way the motherboard manual is written is important. I generally "know" I am going to have questions with some motherboards or their manual. If Gigabyte had clear and specific instructions, would they get or need to deal with these types of questions?

Matt

 

Hi, Going by what I have found googling this question, there are many folks out there that have been seeking answers to these same questions.
I do believe, that it should have been addressed in the manual.

I have today received an answer from Gigabyte, this is the full copy of the reply:

Thank you for your kindly mail and inquiry. About the issue you mentioned, we strongly recommend to use 2X4 pin connector for your motherboard. If only with one 4 pin, it may have unexpected problem.

If you still have any further question or suggestion about our products/service, please do not hesitate to contact us. We will try our best to help you resolve the problem ASAP.

Regards,
GIGABYTE TECHNOLOGY

I have the machine up and running, it actually has been running almost all weekend checking for stability, and she has been running without any hiccups at all.
To my surprise, the HDD that is in the machine was previously in a AMD 939 setup and it booted into Safe mode straight up and all it needed to get into Windows XP was a System Restore from within Safe Mode.
No freezes no BSOD.

My only little disappointment with this board is, it only has DDR2 and not DDR3.
But the range of CPU's it is compatible with makes well up for it.
Counting at the Gigabyte CPU compatibility list for this board, it names a staggering 190 CPU's from AM2, AM2+ and AM3, from AM2 Athlon 64 FX62 to AM3 Phenom II X6 1090T.
If you can believe all that

When my Adapter, 4 pin Molex to 4 pin square arrives I will connect that.
I did include this in my question to Gigabyte, but as you can see no specific reply to it.

Thank you Matt and Mark again for your efforts to help.

hawk22

 

Your welcome

That's a very informative reply from Gigabyte They may make great mobo's but clearly don't spend much time creating comprehensive manuals or answers for there staff to reply with.

Hope it all keeps working well for you.