Question Looking for a 850W PSU.

[balloonshark]

I just bought a used TOXIC AMD Radeon™ RX 6900 XT Air Cooled GPU and need to upgrade my PSU. It will be installed in the system you see in my signature. I'm looking to save a bit of money but I usually go with Seasonic Gold power supplies. The Seasonic Focus Gold fully modular and semi-modular run about $125 and $120.

1. Is 850W enough wattage? Could I get by with a 750W power supply and save some money?
2. Do they have the power connectors the GPU and MB need?
3. What other brands beside Seasonic and Corsair should I consider?
4. I don't keep up with PSU tech but I think I heard something about new connectors. I would rather spend a bit more now to get a power supply that will be compatible with my next build if it is backwards compatible. Are ATX 3.0 / PCI-e 5.0 power supplies backwards compatible with older components?
5. Should I also pick up a power supply tester? If so which do you recommend?

The specs for the GPU are below:

Power Consumption <400W
Minimum 850 Watt Power Supply
2 x 8-pin + 1 x 6-pin Power Connector.

---

* Seasonic Focus GM-850: https://www.amazon.com/Seasonic-Semi-Modular-Warranty-Application-SSR-850GM/dp/B0B9X3BBWD/
* Seasonic FOCUS GX-850: https://www.newegg.com/seasonic-focus-plus-850-gold-ssr-850fx-850w/p/N82E16817151188
* Corsair RM850x (2021) Fully Modular ATX Power Supply - 80 PLUS Gold - Low-Noise Fan - Zero RPM - Black https://www.amazon.com/Corsair-RM850x-Fully-Modular-Supply/dp/B08R5JPTMZ/
* Corsair RM850x SHIFT Fully Modular ATX Power Supply - 80 PLUS Gold - ATX 3.0 - PCIe 5.0 - Zero RPM - Modular Side Interface - Black https://www.amazon.com/Corsair-RM850x-Fully-Modular-Supply/dp/B0BP8BJ7X4/
* Corsair HX850 Fully Modular Ultra-Low Noise ATX Power Supply - Triple EPS12V Connectors 80 Plus Platinum Efficiency https://www.amazon.com/Corsair-HX850-Modular-Ultra-Low-Supply/dp/B0C9KTFXL3/


GPU link for reference: https://www.sapphiretech.com/en/consumer/toxic-radeon-rx-6900-xt-ac-16g-gddr6

I also have 2 spinners, 1 SSD , 3 M.2 drives, 3 case fans and 2x CPU fans installed.

Fractal Design R5 case PSU specs:

PSU max length190/170 mm with a bottom 120/140 mm fan installed or 300 mm when not using any bottom fan location. I have no bottom fans installed at this time but if the GPU runs warm I may install a fan.

 

[Brainonska511]

You couldn't go wrong with any of the PSUs you listed. The Corsair RM and HX series are pretty great.

To throw another one into the ring, what about the RM850e: https://pcpartpicker.com/product/4Z...-fully-modular-atx-power-supply-cp-9020263-na
It's only 140mm deep, so a little on the smaller side. I have the 750W version in 2 machines and they have been pretty great (machine 1 in my sig, machine 2 is an mITX B550 w/5600 and RX 6600).

You might be able to get by with a 750W (maybe punch it all into PCPartPicker), but if any issues crop up, I'm sure people would point to the PSU first. Given what you have in your sig, I'd play it safe and go with the 850W. You aren't saving that much overall by shaving 100W.

Re: power connectors - they should all be fine. Most will have 2 EPS connectors for your mobo, the standard 24-pin, and plenty of PCI-E connectors, likely with at least one that is in a 6+2 config, which, I'd I read correctly, you'll need 2x 8 pin and 1x 6 pin. For Corairs PSUs, you'd really only need 2 cables thanks to their gauging on the pigtail carrying cable (1 for the 8 pin, and then 1 for 8 pin with 6 pin pigtail).

 

[In2Photos]

I agree that any of the PSUs listed will be a good choice. I have the RM850x (non shift). You can see by my sig that I have a 6800XT. I have mine undervolted and it typically sees a little over 200W with the profile I set up. Total system draw for me is about 400-450W based on the Kill-A-Watt reading I took while undergoing all of my testing. Without undervolting the GPU would pull another 70W or so. I like to stay around 50% of the PSU rating for possible power spikes. I think the 850 is a good choice for the 6900XT as well.

The shift is a neat concept. Make sure it is compatible with your case if you go that route. I don't feel like any of the newly released PSUs with the updated connectors are that big of a deal. There will be adapters if you truly need to attach to some new connector. And 12VHPWR is already undergoing a change due to melting.

 

[Brainonska511]

I also wouldn't worry about the newer standards that are slowly rolling out. I have a feeling the current widespread standard will remain for some time, and when the time comes to switch, you'll either be able to buy an adapter, or it will be time to replace the PSU anyway.

 

[balloonshark]

Thank you for your replies. If the shift models are the ones with the connectors on the side they won't work with my case because it has solid metal under my motherboard that would block the connectors. I will strike through those on my list (not that I'm limited to getting only the PSU's on that list).

What about the 2 x 8-pin + 1 x 6-pin Power Connectors for the GPU? (3 total connectors) Where does the 6-pin connection come from? When I look at PSU's I'm not seeing anything that can be used as a 6-pin connector. Do I need a PSU with 3 or more PCIe 8 pin connectors and one of those 8 pins would break down into a 6+2 pin or use a 8 pin to 6 pin adapter? I guess I'm confused because I can't tell if the included PCI-e cables seem to have pigtails on the GPU end. The 2 included PCI-e cables each have 1 PSU end connection with 2x GPU connectors. I know you said the Corsairs 2x8pin connectors would be plenty to power the GPU but does the GPU itself have protection where it won't power on without all 3 connectors? Would a Seasonic gold/platinum PSU have enough juice with only 2x 8 pin PCIe connectors?

I know you all have covered this but I just don't want to make a $130 - $150 mistake. Do the ATX 3.0 / PCI-e 5 power supplies also have all the old connectors I would need for my PC even if I bought a newer model PSU? With my setup would I even use the newer PCIe 5 (12+4 pin) 12VHPWR? As far as I know it goes to the GPU but no idea if they make an adapter for my GPU. I also usually keep a PSU for 5+ years and don't want to buy another PSU if I upgrade my PC in a few years if I can help it.

Sorry if I sound repetitive. I just want to be sure I'm not buying something that will be obsolete in a couple of years.

 

[Brainonska511]

I bought an RM750e earlier in the year and the PCIe 6-pin is just a part of the 8-pin - the 8-pin connectors for PCIe are mostly 6+2 style (ie, you can separate off 2 pins if you don't need them), like the old 20+4 ATX main board connectors. You don't really need to run 3 individual cables to the PSU. Most of them are single 12V rail to start, and good PSUs use properly gauged wires running to the first connector in a pigtailed cable. You're going to be fine on the power front.

As for number of connectors, maybe you need to take a closer look at the manuals on what's included. My RM750e came with a single connector PCIe cable and a pigtailed PCIe connector, for a total of 3 PCI connectors (across 2 cables). You'll want to connect all the GPU ports to power.

For the 12V high power connector, there are plenty of PCIe adapters if you ever buy a card that uses that style. I wouldn't worry about having it natively on the PSU.

 

[In2Photos]

Thank you for your replies. If the shift models are the ones with the connectors on the side they won't work with my case because it has solid metal under my motherboard that would block the connectors. I will strike through those on my list (not that I'm limited to getting only the PSU's on that list).

What about the 2 x 8-pin + 1 x 6-pin Power Connectors for the GPU? (3 total connectors) Where does the 6-pin connection come from? When I look at PSU's I'm not seeing anything that can be used as a 6-pin connector. Do I need a PSU with 3 or more PCIe 8 pin connectors and one of those 8 pins would break down into a 6+2 pin or use a 8 pin to 6 pin adapter? I guess I'm confused because I can't tell if the included PCI-e cables seem to have pigtails on the GPU end. The 2 included PCI-e cables each have 1 PSU end connection with 2x GPU connectors. I know you said the Corsairs 2x8pin connectors would be plenty to power the GPU but does the GPU itself have protection where it won't power on without all 3 connectors? Would a Seasonic gold/platinum PSU have enough juice with only 2x 8 pin PCIe connectors?

I know you all have covered this but I just don't want to make a $130 - $150 mistake. Do the ATX 3.0 / PCI-e 5 power supplies also have all the old connectors I would need for my PC even if I bought a newer model PSU? With my setup would I even use the newer PCIe 5 (12+4 pin) 12VHPWR? As far as I know it goes to the GPU but no idea if they make an adapter for my GPU. I also usually keep a PSU for 5+ years and don't want to buy another PSU if I upgrade my PC in a few years if I can help it.

Sorry if I sound repetitive. I just want to be sure I'm not buying something that will be obsolete in a couple of years.

Technically you could use the shift with your case, but you would have to turn it so that the fan is pointing up and the cables would be towards the left side. That would use air from inside the case to cool the PSU rather than fresh air from outside. And the PSU fan would compete for the air for the GPU fans.

Typically each PCIe cable from a PSU has a pigtail to allow 2 connections. So while there is one connector on the PSU side there would be 2 at the GPU side. 2 cables would give you 4 connectors for the GPU. Some cables are 6+2 pin at the GPU side, but the 8 pin may also just plug right in. I don't believe you would need an adapter. The RM850x for instance shows the GPU side is 6+2. The first Seasonic has 3 cables, but 2 6+2 connectors on each cable.

The new PSUs still have all the connectors you need, they just also include the 12VHPWR. This cable would be of no use to you now, but may be down the road. PSUs without the 12VHPWR would just need an adapter to connect 2/3/4 PCI cables.

 

[balloonshark]

Thanks again to both of you . I ordered the RM850x model. https://www.amazon.com/gp/product/B08R5JPTMZ/r

If you see any issues please let me know. They didn't have the new ATX 3.0 standard in this model unless you got the shift version.

 

[Brainonska511]

Thanks again to both of you . I ordered the RM850x model. https://www.amazon.com/gp/product/B08R5JPTMZ/r

If you see any issues please let me know. They didn't have the new ATX 3.0 standard in this model unless you got the shift version.

You'll be well served by that PSU for a long time. The RM series are consistently highly rated.

 

[In2Photos]

Thanks again to both of you . I ordered the RM850x model. https://www.amazon.com/gp/product/B08R5JPTMZ/r

If you see any issues please let me know. They didn't have the new ATX 3.0 standard in this model unless you got the shift version.

Good choice, it should serve you well.

 

[Ajay]

Thanks again to both of you . I ordered the RM850x model. https://www.amazon.com/gp/product/B08R5JPTMZ/r

If you see any issues please let me know. They didn't have the new ATX 3.0 standard in this model unless you got the shift version.

Good choice! Corsair makes good PSU. After PCPower&Cooling got bought out I’ve used four Corsair PSUs in different computers. Really steady voltage readings over their life.

 

[balloonshark]

My GPU needs 2 x 8-pin + 1 x 6-pin Power Connectors. (3 total connectors needed)

I just had a chat with Corsair. They recommend getting another type 3 or type 4 cable to plug into a CPU/PCI-e PSU connector to go to the extra 6-pin connector on my GPU. The said the PCI-e/CPU connectors on the PSU can be used interchangeably. Is that true?

Recommended cables:

https://www.corsair.com/us/en/p/pc-components-accessories/cp-8920143/type-4-sleeved-black-pcie-cable-with-pigtail-connector-and-capacitors-for-type-4-psu-cp-8920143

https://www.corsair.com/us/en/p/pc-components-accessories/cp-8920111/type-3-sleeved-black-pcie-cable-cp-8920111

The PSU has 2x PCI-e cables included. I also asked about using 1x PCI-e 8 pin and 1x PCI-e 8 pin cable and its 6+2 pigtail for the extra 6 pin GPU connector. They said "You can try that, but it depends on what your GPU manufacturer recommends. Generally single connectors are what is recommended but it can vary." I know you said the Corsair cables would probably handle it but what should I do? Should I try it with the pigtail or order another cable? If so should I get a type 3 or type 4 cable? Which is better, type 3 or type 4? My PSU's cable type says type 4 so I assume it's what I would need.

Also, should I test the PSU? If so what do I need to order to test the PSU? Do you any helpful links on testing tutorials?

 

[In2Photos]

My GPU needs 2 x 8-pin + 1 x 6-pin Power Connectors. (3 total connectors needed)

I just had a chat with Corsair. They recommend getting another type 3 or type 4 cable to plug into a CPU/PCI-e PSU connector to go to the extra 6-pin connector on my GPU. The said the PCI-e/CPU connectors on the PSU can be used interchangeably. Is that true?

Recommended cables:

https://www.corsair.com/us/en/p/pc-components-accessories/cp-8920143/type-4-sleeved-black-pcie-cable-with-pigtail-connector-and-capacitors-for-type-4-psu-cp-8920143

https://www.corsair.com/us/en/p/pc-components-accessories/cp-8920111/type-3-sleeved-black-pcie-cable-cp-8920111

The PSU has 2x PCI-e cables included. I also asked about using 1x PCI-e 8 pin and 1x PCI-e 8 pin cable and its 6+2 pigtail for the extra 6 pin GPU connector. They said "You can try that, but it depends on what your GPU manufacturer recommends. Generally single connectors are what is recommended but it can vary." I know you said the Corsair cables would probably handle it but what should I do? Should I try it with the pigtail or order another cable? If so should I get a type 3 or type 4 cable? Which is better, type 3 or type 4?

Also, should I test the PSU? If so what do I need to order to test the PSU? Do you any helpful links on testing tutorials?

Hmmm, I would say don't trust Corsair support after that conversation!

Based on the image of the PSU from their own website the PSU comes with 3 PCIe cables and each cable has a pigtail for a total of 6 connectors. The GPU is rated at 300W. The PCI slot can provide up to 75W and each PCIe connector is rated for 150W. So 2 cables (using one pigtail) would provide 375W of power. I would still use all 3 cables that should be supplied with the PSU.

 

[Brainonska511]

Hmmm, I would say don't trust Corsair support after that conversation!

Based on the image of the PSU from their own website the PSU comes with 3 PCIe cables and each cable has a pigtail for a total of 6 connectors. The GPU is rated at 300W. The PCI slot can provide up to 75W and each PCIe connector is rated for 150W. So 2 cables (using one pigtail) would provide 375W of power. I would still use all 3 cables that should be supplied with the PSU.

View attachment 86588

Technically, the cables with the pigtails can carry more than 150W in the cable because they use heavier gauge wire up to where the pigtail splits off. You should be fine with what is included with the PSU.

 

[Brainonska511]

For testing a PSU, I bought a cheap tester off Amazon that lets you plug in the key cables and reads off the voltages. Not the best test, since it doesn't show under load conditions, but at least useful to show things are functional and providing the right voltage at near idle conditions.

The only times I've heard it were 1) testing a PSU before install, just to make sure it would turn on, and 2) checking voltages when I had some crashing issues (turns out, it was a faulty GPU).

 

[balloonshark]

Hmmm, I would say don't trust Corsair support after that conversation!

Based on the image of the PSU from their own website the PSU comes with 3 PCIe cables and each cable has a pigtail for a total of 6 connectors. The GPU is rated at 300W. The PCI slot can provide up to 75W and each PCIe connector is rated for 150W. So 2 cables (using one pigtail) would provide 375W of power. I would still use all 3 cables that should be supplied with the PSU.

View attachment 86588

The specs and PSU box says 4x pcie cables but I think they are counting the 2 cables with 2x pigtails for a total of 4 GPU end connectors. The PSU has a total of 5 pcie/cpu connections (2 for pcie and 3x eps/atx12v) The GPU is rated for <400 watts so would 375w be ample power?

Technically, the cables with the pigtails can carry more than 150W in the cable because they use heavier gauge wire up to where the pigtail splits off. You should be fine with what is included with the PSU.

I hope you're correct. I wouldn't mind grabbing another cable but it looks like shipping costs 2x the cable's cost.

For testing a PSU, I bought a cheap tester off Amazon that lets you plug in the key cables and reads off the voltages. Not the best test, since it doesn't show under load conditions, but at least useful to show things are functional and providing the right voltage at near idle conditions.

The only times I've heard it were 1) testing a PSU before install, just to make sure it would turn on, and 2) checking voltages when I had some crashing issues (turns out, it was a faulty GPU).

The person I got my GPU from said to "make sure you do a cold boot loop test with a PSU tester. It's always a good idea to contain any problems to just the PSU if it sparks or blows up." I've never tested a PSU before then again this is my most expensive GPU so maybe it's not a bad idea to test in case the PSU blows up when powering on the first time.

 

[In2Photos]

I just pulled my RM850x box out of storage and it did only have 2 PCIe cables shown on the box, so the image on their website (and Amazon) is wrong. But that also means that I only used 2 cables for my 6800XT which is rated at 272W (my MSI has 3-8 pin connectors on it) and it runs just fine. I believe I pulled a little over 300W during testing before I settled on 200W profile by undervolting. I firmly believe you do NOT need a third cable.

I've never tested a new PSU (and have built a dozen or so new PCs), but a PSU tester isn't a bad thing to have around if you mess with PCs enough.

 

[Brainonska511]

https://a.co/d/9aO19Ek is the tester I bought a few years ago. Cheap (it was $15) and effective. Not currently available, but gives you an idea of what to look for.

As for the PSU cables, you'll be fine with 2. Corsair uses 16 gauge wiring up to the first connector, then 18 gauge from the first connector to the pigtailed connector. Plus, all these PSUs are single 12V rail. Spreading stuff out over more connections can be beneficial, but you'll be fine if you use 2 (with one utilizing the pigtail). If you see anything funky happening, then pick up the 3rd cable (provided it is the right type - don't mix type 3 and type 4; follow whatever the manual says).

I saw someone once say that the pigtailed cables may top off at ~275 W for the entire cable, so you'd have 150W for one solo plug, then 275 W across an 8 pin + 6 pin, plus 75 W of slot power, more than enough. The rating is of course a bit of hearsay, but the cable gauges are published by Corsair, so you can at least see they use heavier gauging up to connector #1.

I really loathe how they include the pigtailed connectors, but then don't publish any details about power ratings, and then also say that pigtails shouldn't really be used. Don't sell things if they officially shouldn't be used that way (or it's some weird cover their butts sort of thing).

 

[nightspydk]

Cannot read through all this but I have the Corsair RM850x and I am using one 6+2 pin on my GPU no problem. I tried the CPU cable 8 pin on there and it didn't work for me so you might have a problem there (I believe it didn't even fit in the socket). I have a RTX 3060ti. I like the fact they go silent on low system load. All cables and ports are labeled. It's a shame tho they have 2 * 6 pins together for the GPU with one +2. All excess mess in the Box.

Have very good experience with corsair PSUs. One 650W modular going on 5+years strong.

Good luck and hope that helps a bit

*edited

 

[Brainonska511]

Cannot read through all this but I have the Corsair RM850x and I am using one 6+2 pin on my GPU no problem. I tried the CPU cable 8 pin on there and it didn't work for me so you might have a problem there (I believe it didn't even fit in the socket). I have a RTX 3060ti. I like the fact they go silent on low system load. All cables and ports are labeled. It's a shame tho they have 2 * 6 pins together for the GPU with one +2. All excess mess in the Box.

Have very good experience with corsair PSUs. One 650W modular going on 5+years strong.

Good luck and hope that helps a bit

*edited

Yeah, don't use the EPS 4+4 connector (or solid 8-pin) on a GPU.

On my RM750e paired with a 7800 XT, I just use the single 6+2 with the 6+2 pigtail to power it all. Keeps the cabling neat. (They also included a single 6+2 cable without the pigtail, but I'd need a second cable).

 

[balloonshark]

I should have followed up on this topic when I installed the PSU. The box is too hard to get to at the moment. I did pick up the extra cable but once I got the PSU I think enough cables were included so it was a waste of money. I have 3 cables going to the GPU and it looks like a mess. I could remove one like suggested but my case has no windows so it's not a big deal. I also think I'm using all 5 PCI-e/CPU connections on the PSU (2x CPU and 3x PCI-e).

Also, I want to be clear that they said the PCI-e and CPU connections on the PSU can be used interchangeably. The PCI-e and CPU cables themselves can not be used interchangeably as pointed out by Brainonska511.