Adventures in 20 pin PSU's and 3870's - Techist - Tech Forum

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Old 04-09-2009, 11:35 AM   #1 (permalink)
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Location: Austin, TX
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Default Adventures in 20 pin PSU's and 3870's

A sort of experiment underway.
Can I use a newoldstock Antec 380 Truepower with a 20pin adapter on a 24 pin Asus mobo?
... in a mostly low-power (except for a 3870 card) build?

I know most people suggest buying a new PSU rather than "risk it" but I'd like to recycle a decent piece of equipment if I can. (why scrap an unused antec/seasonic?) Plus I'd like to use the minimal PSU I need.

You can use a 20pin on a 24pin mobo since the 4 pins power the PCI-E slot. Not a problem with none or minimal PCI-e, but what about a card that takes a PCI-e connector? (how does it balance between the PSU and mobo source?)

mobo: Asus M3A78-EM (onboard 780G)
cpu: 5050e lower power
one sata optical drive one 500GB sata HD
current graphics: HD 2400 Pro (in hybrid crossfire no less :-)
It drew about 80 watts at idle 140 at load.

The case is a new Rosewill that came with a 400W PSU (Delta mfctr). (*I am familiar with the standard disclaimers about using cheap case PSU's and their limited efficiency.) The power supply has 14 and 13amp 12V rails. The power cable has only two principal lines, one with a single sata (my HDD) and one with a sata (my DVD) and two 4 pin molex (free).

Rosewill designed this so you can't really put much load on the PSU.

With a pci-e 6 pin adapter to the 2 molex I can run the 3870, but I'm not sure how the power load is distributed and whether the system will be stable under use

My quirk is that I use graphics cards for algorithm processing (like folding@home) rather than gaming, so my power loads tend to be more stable but they can still push my needs up to 200 watts.

The Antec is new old stock and has more amps (17 per rail) and better distribution. My 24pin 380 Earthwatts is handling a similar rig (AMD 5600+ and 3870) with no problems.

Should I stick with the Rosewill, resurrect the Antec, or give up the 3870 in this system?

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Old 04-09-2009, 12:05 PM   #2 (permalink)
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Default Re: Adventures in 20 pin PSU's and 3870's

i would try the antec first, then if you feel it's not up to the job then try the rosewill. but the antec should be fine

The only thing ATi can render faster than nVidia is the BSOD


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