I'm currently trying to add a GTX 1060 6GB card to my server for a VM but I don't believe I have a way to power it. I currently have a Supermicro 846BA-R920B chassis with X9DRi-LN4F+ mobo. The chassis has PDB-PT846-8824 as the power distribution which does not have a 6 pin connector for a GPU. One solution I have come across is using molex to 6-pin adapters but I currently have all of the molex connections in use due to the backplane and 2 SSD's. It looks like I only have a 4-pin connector remaining. 

 

One way I could get the 2 molex connectors from the SSD's is by putting them in the front drive trays so they are connected to the backplane. The only issue I would have with that is I believe TRIM is not supported. 

 

Do I have any other options or does anyone have any suggestions? 

independent power supply? (I've actually done this... not super recommended, but possible.)

Buy the molex to 6-pin adapter and some molex spitters and you're done?

Yeah I’ve read about independent power supply but I’d just rather not lol. And I can’t believe I didn’t think of the molex splitter... always overlook the simple solution. And I guess I’ll have to do the math on this but I think I have enough wattage? 920W redundant power supplies, 2x e5 2650v2, 12 sticks of ram, 26 drives. I believe that’s around ~550W worst case? 

 

Looks like worst case draw from this gpu could be ~200W putting me at 750W of my 920W. 

 

So if I were to use the molex splitters..

 

Taking the 2 molex’s that are being used for the 2 SSDs and splitting each of them puts me at 4 molex connectors. Take one end from each splitter and use those for the molex to 6-pin for the GPU. That leaves one molex from each original connector for each SSD. 

 

Is this safe to do and will the GPU have enough power along side the SSDs? 

 

Im seeing mixed responses from my searches about how much power a molex can provide and wether or not it works. 

 

You're using molex connectors to power your backplane right? Use the splitters there to free up two molex to connect to your 6 pin adapter. Don't use splitters on the 6 pin adapter.

 

Edit: I haven't done the math, but sounds like you have so you're probably good. And I use splitters on my backplane too and I have no issues. But then again they are only powering drives.

Edited December 30, 20187 yr by strike

12 minutes ago, strike said:

You're using molex connectors to power your backplane right? Use the splitters there to free up two molex to connect to your 6 pin adapter. Don't use splitters on the 6 pin adapter.

 

Edit: I haven't done the math, but sounds like you have so you're probably good. And I use splitters on my backplane too and I have no issues. But then again they are only powering drives.

I do have molex connectors being used for the backplane however I believe those are powering multiple drives each? 

 

I have 2 additional molex connectors being used for SSDs. I made a crude drawing on my phone of what I would do if I used the splitters. 

 

These molex connections are in addition to what is already used on the backplane. 

 

And for power delivery I’ve seen varying responses of each molex cable being able to deliver 40W some saying 75W so it’s hard to tell if it’ll be able to power the card. I know the psu can handle it, I just can’t wrap my head around why the PSU has such a high wattage if there aren’t enough connections to even saturate it. 

Yes, the backplane molex connectors do power multiple drives. I think my backplane is powered by 6 molex which delivers power to all 24 drives (1 molex powers 4 drives). IIRC I use 2 or 3 splitters and have never had any issues. To be safe you should use only 1 splitter per molex cable. As I said I would not use the splitters as you suggested, use them on your backplane instead.

16 minutes ago, strike said:

Yes, the backplane molex connectors do power multiple drives. I think my backplane is powered by 6 molex which delivers power to all 24 drives (1 molex powers 4 drives). IIRC I use 2 or 3 splitters and have never had any issues. To be safe you should use only 1 splitter per molex cable. As I said I would not use the splitters as you suggested, use them on your backplane instead.

I've attached what I think is a more clear image now that I am at a computer. I do have only one molex splitter per molex cable. Say my backplane only uses 6 molex connections, I have 2 additional connections that are not required for the backplane giving me 8 total connections. 

 

 

I guess my only question now is can 2 molex connections successfully power this GPU and 2 SSDs? 

I did understand your drawing the first time  , but I still don't think you should do it that way. To be sure the GPU gets all the power it needs you should not use splitters on it.

 

Think about it, you're splitting a power connector into 2 connectors, which each can power half of the original connector. You then have 0,5+0,5=1. You do the same with one more molex and you also get 0,5+0,5=1. If we add them up we get 2, right?

 

Now you want to power a 6 pin adapter which uses two full molex connectors, and you want to only take half (0,5) of each original molex connector which is= 0,5+0,5=1.

If you need 2 molex connectors, then how do you think you'll do with two halves (=1)..?

 

The GPU draws more power then 4 drives connected to one molex. So again, I'm not forcing you to do anything here, but I believe your best bet is to use the splitters on your backplane. Then use the two molex you free up there  on your GPU.

 

45 minutes ago, Chandler said:

I guess my only question now is can 2 molex connections successfully power this GPU and 2 SSDs? 

 

So to answer this.. The way you suggested, The SSDs yes, the GPU not so much. If you try it my way, then yes maybe. I could be wrong though, it happens all the time..

 

 

Edited December 31, 20187 yr by strike

5 minutes ago, strike said:

snip

Ah so are you suggesting I split molex's off the backplane to power the SSDs. Then use the 2 molex's that were powering the SSDs to solely power the GPU with a molex to 6-pin adapter? 

lol, now you're trolling me right?  But yeah, you could do that too. Whatever floats your boat as long as the two molex you're using for the gpu are not split.

3 minutes ago, strike said:

lol, now you're trolling me right?  But yeah, you could do that too. Whatever floats your boat as long as the two molex you're using for the gpu are not split.

Ok now after re-reading your original post I see thats what you were saying. Yeah in my head that didn't connect because of how I visually see how it is all wired in the server. 

 

And after I did some thinking about how a 6-pin connector only delivers 75W and the GPU takes ~120W which doesn't add up. I remembered that the PCIe slot provides power itself. Looks like the slot provides 75W and a 6-pin connector supplies 75W as well adding up to 150W. 

 

If each molex carries 40W like the internet says that is 80W which is enough for the 6-pin to saturate it and provide a combined up to 150W to the card which should power it to its max power draw.