Topic: Add second PSU to my rig (Read 186 times)

Generally its not a good idea to run a PSU with no load, so if you are worried about that just attach a small fan to the 2nd PSU.

Just make sure that only one of your PSU’s powers the motherboard – meaning that the same PSU connects to the 24 pin power connector and the 8 pin CPU power connector, all should feed back to the same power supply.

connecting 5V (red) with the ground it's enough. 5V dummy load on 24 Pins just to make sure our PSU produce the right wattage, you can measure it your self. if without dummy load your PSU produce the right wattage, you don't need to do it.

Oh I did not know about 5V dummy load. What kind of load do you suggest to put on 5V?

Google found this: https://pcbsmoke.wordpress.com/2012/11/21/converting-an-atx-power-supply-into-a-dc-bench-supply/

"Q. Which power rail do I install the dummy load resistor on?
A. As a general rule, you install the dummy load on either the +5 volt rail or the +12 volt rail, whichever one has the most power."

Modern Power supply have most Power on 12 V and since we already connect GPU and risers maybe we don't need any dummy load?

So, you didn't have enough connector for powering the 4th GPU and you plan to add one more PSU to powering the 4th GPU or maybe you will powering two or more GPU with 2nd PSU, my assumption since you didn't say how much power your 1st and 2nd PSU. It's okay with that scheme, but always calculate the power consumptions of your device.


If we are trying to do jump-start, make sure give dummy load on 5v.

Basic guidelines with multi-PSU rigs:
Use one PSU to power the board's main connection (dual PSU cables shouldn't wire all the connections from both 20/24-pin main connectors; it should only have all the cables for one connector, then the other should only have the green pin and one ground connected). Use this same PSU to power the 4/8-pin CPU connection(s) on the motherboard. Generally this PSU should also be used to power the storage device, but that is not necessarily a requirement. Ensure that the other PSU only deals with graphics cards and risers.

Ensure that you distribute the load such that neither one of the PSUs is over 70-80% of its rating. Despite the "Add2PSU" name, you're not truly getting the effects of a single PSU; appropriate load distribution remains your responsibility.

If you're like me and choose not to use an Add2PSU device or dual PSU cable, ensure that the secondary PSU is powered on before hitting the boot switch to turn on the primary (connected to the motherboard) PSU.

As always, but especially in this case, use quality PSUs. Adding more PSUs in a nonredundant configuration, as is typical, can add more points of failure. For example, if EITHER unit fails, it may result in downtime for the entire rig. (If the primary PSU fails, this is the obvious result. However, if the secondary PSU were to fail, it may or may not be the case that the rig can continue mining with the graphics cards connected to the primary PSU. Oftentimes, a power failure to some of the cards can cause the mining software/drivers/OS to throw an error, downing the entire system.)
Using quality PSUs is especially important when each represents its own possible point of failure for your rig. Look for quality OEMs such as Seasonic, FSP, and Superflower. (HEC, CWT, Sirfa/Sirtec are definitely lower on the totem pole, but better than no-name units. I personally don't use these for mining rigs, where the are under heavy loads 24/7, but I've used their units for home use and they usually do the job.)

You should pick up one of these, (see link Below) to allow your motherboard to power on both power supplies at the same time,
https://www.amazon.com/gp/product/B00O0M6Q0C/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1

well that one seems to be out of stock as a shipped by Amazon product, but you get the point, scroll down and you will find 10 similar items for 15$ or less, I linked that, simply because that is what I own, and I know they work well, but the others available should work just as well, they simply link two power supplies to your Motherboard, and allow them to both turn on simultaneously

Yes, that is possible, you can power risers and MB and cpu from one power supply, while power up all your four gpus from another power supply, all you need is just sync them, so once you start first one, the second one also starts.

Yes, there is no harm by doing so.
You can also lesser the wear and tear strain from your first PSU by distributing the cards among the two PowerSupply. (2Cards/PSU)

Maybe but what are you planning .?

Five or six later on.

Or just four cards

Hello. I'm looking to add a second power supply to my rig. I currently have 1 psu powering everything (mobo, ssd, cpu, 3 gpus, 3 risers). I just got a 4th gpu and looking to connect it to second psu (first psu doesn't have enough connectors). I will also need Add2psu to turn on/off both psu at the same time

So do you think it's ok to just connect a gpu and a riser only on second power supply?