PSU with 3 8-pin ports (can it run 2x 4+4 CPU?)

[Guy Marshall]

I have a Corsair RM650 and am wanting to upgrade from my FX-8350 to the 2990wx. The motherboard I am looking at (the MEG creation) has 2x 4+4 CPU connectors. My PSU at the back has 3 identical ports labelled "6+2 PCI-E & 4+4 CPU" but has no indication as to which is which. The total usage of my system (250W for CPU + 200W for GPU) means I will not necessarily need an upgraded PSU for power consumption alone.

 

My question is can I plug a second 4+4 CPU cable into one of those ports to go to the motherboard? I currently have 1 spare as my Strix 970 only uses 1. I also tried the connectors and they both fit in each of the 3 ports on the PSU, making me feel like another CPU power cable can go in there!

 

Also secondly, can I run the CPU at stock settings with just 1 CPU power connector into the motherboard until I order another CPU power cable if I need to at all?  I will not be manually overclocking because I want the increased single core performance from PB and PBO.

 

Thanks in advance

[GoldenLag]

If its laveled as both, then it is both.

 

Also

 

20 minutes ago, Guy Marshall said:

from my FX-8350 to the 2990wx.

Why upgrade to the rendering only CPU that is the 2990wx with threadripper 3 right around the corner? Aswell as 16 core ryzen?

 

Seems like a waste to me, regardless of your usecase.

[Guy Marshall]

1 minute ago, GoldenLag said:

If its laveled as both, then it is both.

 

Also

 

Why upgrade to the rendering only CPU that is the 2990wx with threadripper 3 right around the corner? Aswell as 16 core ryzen?

 

Seems like a waste to me, regardless of your usecase.

Thank you for your reply, and yeah I thought they were both CPU and PCI-E in one because the port fits for both but just needed to check!

 

I am waiting until the 3990x comes out, and then deciding if I need the doubling of threads, or if I should go with the cheaper CPU. I just need a massive upgrade over my 8350 for intense physics calculations that take many weeks to complete (will take months once more are added). The 3950x will still take far too long to calculate  My usecase needs lots of threads and high clock speed and IPC helps.

[GoldenLag]

10 minutes ago, Guy Marshall said:

The 3950x will still take far too long to calculate  My usecase needs lots of threads and high clock speed and IPC helps.

the issue is that the 3950x AM4 CPU is likely to be almost as fast as the 2990wx. 

 

24 core Zen 2 should theoretically, judging by Epyc 7002 pricing start at 1200-1400$. that would be a much better option.

 

12 minutes ago, Guy Marshall said:

Thank you for your reply, and yeah I thought they were both CPU and PCI-E in one because the port fits for both but just needed to check!

just doublecheck that the name on the cable agrees aswell. they originally use slightly different gauge wires. the 6+2 pin PCIe topping out at 180w i believe it is. and the 4+4 pin EPS tops out at 384 watts. (minimum spec)

[Guy Marshall]

1 minute ago, GoldenLag said:

the issue is that the 3950x AM4 CPU is likely to be almost as fast as the 2990wx. 

 

24 core Zen 2 should theoretically, judging by Epyc 7002 pricing start at 1200-1400$. that would be a much better option.

 

just doublecheck that the name on the cable agrees aswell. they originally use slightly different gauge wires. the 6+2 pin PCIe topping out at 180w i believe it is. and the 4+4 pin EPS tops out at 384 watts. (minimum spec)

Okay thanks I will look into those  I'll have to buy a second cable (on Amazon) but am unsure of how cheap a cable I should order as it is powering my CPU after all

[GoldenLag]

Just now, Guy Marshall said:

 I'll have to buy a second cable (on Amazon) but am unsure of how cheap a cable I should order as it is powering my CPU after all

watch out for PSU compatibility. not all PSUs use the same end at the output. 

 

 

and unless you are overclocking hard, its likely you can just run a single 8 pin. you wont exceed 384w, and its likely the board and PSU use the higher spec gauge aswell. 

[Guy Marshall]

1 minute ago, GoldenLag said:

watch out for PSU compatibility. not all PSUs use the same end at the output. 

 

 

and unless you are overclocking hard, its likely you can just run a single 8 pin. you wont exceed 384w, and its likely the board and PSU use the higher spec gauge aswell. 

Oh okay I thought all 8 pin connectors were the same! Also I can only find 2x 4 pin cable extensions to go into an 8 pin on the motherboard like this: https://www.amazon.co.uk/Akasa-AK-CBPW08-40BK-Flexa-ATX12V-Extension/dp/B004ZKXUS0/ref=sr_1_7 ?

 

Do you know where I  can get an 8 pin to 8 pin directly from the PSU and not an extension?

[paddy-stone]

https://www.corsair.com/us/en/Categories/Products/Accessories-|-Parts/PC-Components/Power-Supplies/Type-4-Sleeved-black-8-pin-(4%2B4)-ATX12V-EPS12V-Cable%2C-compatible-with-all-CORSAIR-type-4-pin-out-PSU/p/CP-8920141

[Guy Marshall]

1 minute ago, paddy-stone said:

https://www.corsair.com/us/en/Categories/Products/Accessories-|-Parts/PC-Components/Power-Supplies/Type-4-Sleeved-black-8-pin-(4%2B4)-ATX12V-EPS12V-Cable%2C-compatible-with-all-CORSAIR-type-4-pin-out-PSU/p/CP-8920141

Thank you very much

[paddy-stone]

Just now, Guy Marshall said:

Thank you very much

No worries, was a quick find... also it's not in stock right now, but has a "notify me when in stock" clicky.

[Guy Marshall]

Just now, paddy-stone said:

No worries, was a quick find... also it's not in stock right now, but has a "notify me when in stock" clicky.

I'm in the UK so it's in stock for me  

[paddy-stone]

3 minutes ago, Guy Marshall said:

I'm in the UK so it's in stock for me  

Even better

 

[paddy-stone]

That's one thing I'll give to Corsair... they make it simple to change countries for their urls, I just swapped the s in us for a k

 

[Guy Marshall]

Just now, paddy-stone said:

That's one thing I'll give to Corsair... they make it simple to change countries for their urls, I just swapped the s in us for a k

 

Yeah they definitely do! I was expecting the classic "Product page does not exist, make sure you spelled it correctly" but I was amazed that it just appeared in good old quid

[GoldenLag]

22 minutes ago, Guy Marshall said:

I'm in the UK so it's in stock for me  

if you have a single 8 pin EPS, unless you do some hefty overclocking, then you should be more than fine with a single connector. a second EPS connector is far from required. in fact its mostly a useless connector, especially on consumer boards. 

[Guy Marshall]

22 minutes ago, GoldenLag said:

if you have a single 8 pin EPS, unless you do some hefty overclocking, then you should be more than fine with a single connector. a second EPS connector is far from required. in fact its mostly a useless connector, especially on consumer boards. 

Okay thank you for that information I might just get a spare one just in case I need to in the future then!

[mariushm]

 

Corsair RM 650 has 4 connectors on it, in which you can insert either EPS or PCI-e cables.

The reviews say that this model has 2 EPS cables, each with one 8 pin EPS connector at the end.

If you have only one cable, you can buy an extra one from websites like cablemod

 

You can't use a 6pin or 8pin pci-e cable to power the processor, the order of the wires is different.

 

The 2990WX can consume up to a bit below 250 watts depending on workload (how many threads are working).

While a single 8 pin EPS connector is good for up to around 330-430w, let's just say 380w as a safe value - connectors are rated for 9A of current, but due to how close they are together, EPS recommends not going over 7A, so you have 4 pairs of wires x 7A x 12v = 330w minimum) - it's a good idea to add the 2nd power cable because it will result in less losses through the wires, and the connectors and wires will heat less.

 

 

[Guy Marshall]

16 minutes ago, mariushm said:

 

Corsair RM 650 has 4 connectors on it, in which you can insert either EPS or PCI-e cables.

The reviews say that this model has 2 EPS cables, each with one 8 pin EPS connector at the end.

If you have only one cable, you can buy an extra one from websites like cablemod

 

You can't use a 6pin or 8pin pci-e cable to power the processor, the order of the wires is different.

 

The 2990WX can consume up to a bit below 250 watts depending on workload (how many threads are working).

While a single 8 pin EPS connector is good for up to around 330-430w, let's just say 380w as a safe value - connectors are rated for 9A of current, but due to how close they are together, EPS recommends not going over 7A, so you have 4 pairs of wires x 7A x 12v = 330w minimum) - it's a good idea to add the 2nd power cable because it will result in less losses through the wires, and the connectors and wires will heat less.

 

 

Okay thanks for that info! I have just checked and my RM650 has 3 8-pin connectors which are labelled as both CPU 4+4 and PCI-E 6+2 so I am presuming that they can be used for either CPU or PCI-E without issue. I will plug in a second CPU just to be on the safe side, and in case I decide to overclock in the future for whatever reason