Is 8 pin cpu eps to dual 8 pin pcie adapter safe to use?

[Woodduck42]

I'm building a SFF PC with a 7900xtx and a motherboard that uses an external AC-DC PSU. The HDPLEX 500w PSU is one of the only PSUs that will fit my build but it only has a single PCIe power connector as shown in the attached image. Would I be able to use an EPS to PCIe adapter to power the gpu?

[filpo]

7 minutes ago, Woodduck42 said:

The HDPLEX 500w PSU is one o

500w is definitely not gonna be enough for a 7900 xtx (if you plan to game on it)

 

7 minutes ago, Woodduck42 said:

Would I be able to use an EPS to PCIe adapter to power the gpu?

Well yes, but not on such a low power psu. If you're planning to have a decently high power cpu or even a 7800X3D it won't run below that 500w

here's an example system's wattage TLDR: it's 596W, you're unlikely to hit 600W while gaming but you'll defo break 500. Btw this is with the most efficient gaming cpu of them all so if you've got an intel K chip I wouldn't advise using this or under volt immediately (7800X3D, 7900 xtx, A620 (though you'll probs have a B board), 32 gigs of 5600 CL28, A 2tb gen 4 ssd, no dram) Also I didn't put any psu since it wasn't really needed

PCPartPicker Part List

CPU: AMD Ryzen 7 7800X3D 4.2 GHz 8-Core Processor  ($389.00 @ Amazon) 
CPU Cooler: Thermalright AXP90-X47 42.58 CFM CPU Cooler  ($22.90 @ Amazon) 
Motherboard: ASRock A620I LIGHTNING WIFI Mini ITX AM5 Motherboard  ($139.99 @ Newegg) 
Memory: *G.Skill Ripjaws S5 32 GB (2 x 16 GB) DDR5-5600 CL28 Memory  ($103.99 @ Amazon) 
Storage: *TEAMGROUP MP44L 2 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive  ($98.25 @ Amazon) 
Video Card: *XFX Speedster MERC 310 Black Edition Radeon RX 7900 XTX 24 GB Video Card  ($944.99 @ Amazon) 
Total: $1699.12
Prices include shipping, taxes, and discounts when available
*Lowest price parts chosen from parametric criteria
Generated by PCPartPicker 2024-01-25 13:50 EST-0500

[Woodduck42]

I will be using this PSU to power the gpu only. The motherboard and cpu uses an external power supply so I have no need for the 24 pin or molex connector. Doesn't the 7900xtx only use 350 watts? I know 500w total power capacity ≠ 500w capacity on the 12v rail always but still it should be able to handle 350w? My lunch break is over I will revisit this thread when I'm on my coffee break.

[filpo]

1 minute ago, Woodduck42 said:

Doesn't the 7900xtx only use 350 watts?

it can use more but stock it should, yes 

 

1 minute ago, Woodduck42 said:

I know 500w total power capacity ≠ 500w capacity on the 12v rail always but still it should be able to handle 350w?

oh yes definitely, I thought you were talking about the whole pc with that 500w psu. But surely if you're powering the rest of the system with a different psu you should be able to fit an sfx psu in the case?

2 minutes ago, Woodduck42 said:

The motherboard and cpu uses an external power supply

how big is that psu? Also which case are you using for the components?

[PDifolco]

1 hour ago, Woodduck42 said:

I will be using this PSU to power the gpu only. The motherboard and cpu uses an external power supply so I have no need for the 24 pin or molex connector. Doesn't the 7900xtx only use 350 watts? I know 500w total power capacity ≠ 500w capacity on the 12v rail always but still it should be able to handle 350w? My lunch break is over I will revisit this thread when I'm on my coffee break.

Well can't you power everything with an internal 750W+ PSU ?

Makes no real sense to get a SFF build and then an external PSU...

 

 

[Bismut]

1 hour ago, filpo said:

500w is definitely not gonna be enough for a 7900 xtx (if you plan to game on it)

It might be okay for the entire system, depending on the CPU and load. I have undervolted my CPU, significantly lowering its power draw, and would assume OP knows what they are doing, i.e. is either planning on undervolting (even downclocking) or (as added in their 2nd post) using a 2nd PSU.

 

1 hour ago, filpo said:

If you're planning to have a decently high power cpu or even a 7800X3D it won't run below that 500w

here's an example system's wattage TLDR: it's 596W

Man, this world has become crazy. 600W is A LOT of power to draw for longer periods of time. Not relevant to the post, I just wanted to say it

 

1 hour ago, Woodduck42 said:

Doesn't the 7900xtx only use 350 watts? I know 500w total power capacity ≠ 500w capacity on the 12v rail always but still it should be able to handle 350w?

I have heard that a good PSU is able to provide almost all its rated power at the 12V rail. IDK whether that is still current, but I would also hope that HDPlex built some headroom into their PSUs, given what people have been doing with them in the past.

 

5 minutes ago, PDifolco said:

Well can't you power everything with an internal 750W+ PSU ?

Makes no real sense to get a SFF build and then an external PSU...

I agree, unless you are running it off a generator/battery backup/cigarette lighter socket (in which case: good luck). I get that SFX is sort of clunky (I wish there was a widely adopted, flatter PSU standart), but have never understood the idea of an external PSU either. Especially when you are running a 7900 XTX, which is a massive card due to its huge power draw.

[Woodduck42]

 

1 hour ago, PDifolco said:

Makes no real sense to get a SFF build and then an external PSU...

The PSU is basically a larger phone wall wart so I justified it. It would be different my build was using a large laptop brick.

 

2 hours ago, filpo said:

how big is that psu? Also which case are you using for the components?

PSU dimensions are attached below. Pretty small and it's unique form factor allows me to fit it in my case. (TFX and flexATX doesn't fit).

I want to keep the specifics about the case and layout under wraps for now because I think it's quite a unique case/build. I've physically measured everything so I'm confident the HDPLEX is the only non sketchy PSU (don't really want to burn my house down with a Picopsu or something like that lol)

 

I'll revisit this thread when I'm home from work.