PSU Recommendation for SLI

[mdahc]

I'm thinking of getting a couple of Leadtek PCIe 6600 GT's (b/c of the included HDTV dongle, noise and cooling levels, and PureVideo) along with an A8N-SLI, and I'd like to avoid getting a new PSU. I currently have an Antec NeoPower 480W PSU. Do you think this will suffice?

Current System Specs:
AMD Athlon64 3200+ (s939 Winchester core, OC'd to 2.2GHz)
MSI K8N Neo2 Platinum (BIOS v. 1.40)
1GB OCZ DDR466 Rev. 3 (running at 2.5, 4, 4, 10, 2.8V, 220MHz)
single 36.7GB WD Raptor HDD
external 40GB Firewire 400 HDD
Sony DDU1612 DVD-ROM
eVGA 6600 GT AGP
Antec NeoPower 480W PSU
Lian-Li PC-V1000 silver case
Sony CPD/E540B 21" Trinitron CRT

 

[Ronin]

With the 2 +12V rails on that (@18A and 16A), I think you should be ok. I decided I wasn't going to take any chances, and am going with the 680W TT (3 +12V rails), but I think you'll be fine with what you have.

 

[mdahc]

I hope so. I guess if it's not enough, I could always just get another PSU. Thanks.

 

[HardWarrior]

Originally posted by: mdahc
I hope so. I guess if it's not enough, I could always just get another PSU. Thanks.

You don't have to go THAT far unless you just want to. There was a thread in CASES & COOLING that discussed the issue. I think I saw mention of an Enermax that was designed for SLI, though I'm not sure.

Ronin: If your case doesn't burn very much power any power that's left is going to expended as heat, which in turn will lower the efficiency and life of your PSU. I read this AFTER I bought my 600w. 🙁

 

[Ronin]

HardWarrior: With 5 case fans, 2 optical drives, at least 2 striped HD's, 2 6800U"s and a FX55 (both of which will be overclocked), among various other nuances, I expect the draw to be fairly healthy.

 

[HardWarrior]

Originally posted by: Ronin
HardWarrior: With 5 case fans, 2 optical drives, at least 2 striped HD's, 2 6800U"s and a FX55 (both of which will be overclocked), among various other nuances, I expect the draw to be fairly healthy.

Yeah, you'll be fine. 🙂

 

[VirtualLarry]

Originally posted by: HardWarrior
Ronin: If your case doesn't burn very much power any power that's left is going to expended as heat, which in turn will lower the efficiency and life of your PSU. I read this AFTER I bought my 600w. 🙁

Hmm?

I think that you heard that wrong.

AFAIK, for a linear supply, that may be true, but not for a modern switching power-supply as used in PCs.

If you buy a PSU with a "600W max" rating, and your rig only draws 200W steady-state, that does NOT mean that the PSU dissapates 400W as heat.

Now, there is this matter of efficiency, and power-factor, etc., and most PSUs are designed to have a sort of "sweet spot" in terms of the preferred load range. (And in fact, don't operate correctly without a load.)

So it's possible that conversion effeciency may drop slightly, and, as a percentage function of the load drawn from the PSU, the amount of wasted power and therefore waste heat may increase - slightly, but it's not like the PSU always generates 600W of DC power and has to dissapate the unused power as waste heat.

In contrast, those little "power bricks" used to convert AC to DC for small electronics devices are linear supplies (if they are heavy, most are), and they get rather warm, even when the device that they are powering, is turned off and not drawing any power. If you ever get a chance to check out a switching version of those bricks (used for some laptop's AC adaptors), you'll note that they mostly don't get as hot, unless they are under load and currently powering something.

Also, AFAIK, running a switching PSU at lower levels of efficiency does not in itself lower the lifetime of the PSU, but heat in general does. PSUs that run hot, tend to not live as long. You can check the temp of the exhaust air from the PSU - I prefer it to be no hotter than lukewarm, if that. Otherwise I suggest better cooling or a more-powerful supply.

 

[HardWarrior]

No, I didn't hear it wrong, VL. I saw it in a review and then danced around overclockers for a couple of days with it.