Power supply for A64?

limee · Post by **limee** » Sun Jan 25, 2004 11:30 am

Hi, how high power and +12v amp rails should I be looking at for use with an A64 3k+ and two 80 gig hard drives in raid 0?

Equilateral · Post by **Equilateral** » Mon Jan 26, 2004 8:25 pm

how high power and +12v amp rails should I be looking at for use with an A64 3k+ and two 80 gig hard drives in raid 0?

Ahh, now that gets interesting, because figures for this are really hard to find (even AMD are completely useless for this, they just have some boilerplate up about "make sure you do everything right"). The only vendor that I could find that published figures is MSI, who list a range of power supplies tested with a very lightweight system, an A64 2900 (presumably a engineering sample, since there's no such thing), 128 MB DDR266, an MX400, and no HDD or CDROM. In other words the only load on the 12V rail is the CPU, you'd need to add another 2-3A per HDD and 1-2A for a CDROM (that's worst-case). In addition I suspect they didn't stress the system too much, merely got it to the BIOS setup screen rather than running Windows/Linux - even a Deer power supply will usually get a system to the BIOS setup without catching fire.

That's the bad news. The better news is that even supplies rated at 235-250W (FSP250, LC235, SS250) were OK for this minimal test. The majority were in the 300W-rated class. So I'd take the rating of those supplies, add a few amps for other devices, add a 20% fudge factor, and that should be OK, and if it isn't, well I'm on the other side of the planet from you when your system blows up so I'm not worried :-).

halcyon · Post by **halcyon** » Tue Jan 27, 2004 1:21 am

http://takaman.jp/psu_calc.html?english

89W max for current generation Athlon 64 series.

regards,
Halcyon

limee · Post by **limee** » Tue Jan 27, 2004 6:49 pm

Equilateral: I'll shoot at around 20A, should be safe from what I hear. Too bad AMD couldn't give a straight answer...

Halcyon: 89W? Not as bad as I thought

Thanks for the help guys, was paranoid I'd have to get a PSU in excess of 400 watts!

halcyon · Post by **halcyon** » Tue Jan 27, 2004 11:53 pm

limee,

Yesm that 89W includes all models in the current manufacturing process line. This is specified in AMD documentation.

That is absolutely maximum thermal power draw. Not some prettied up calculation about averages, like Intel tends to give about P4 line.

So in reality, unless you are buying Athlon 64 FX 53 (not available yet) you should get by with even less wattage.

regards,
halcyon

Jan Kivar · Post by **Jan Kivar** » Wed Jan 28, 2004 12:52 pm

The 89 W figure is "Thermal design spec" for HSF manufacturers, so that they could design one cooler for the entire AMD 64 line. I think that the models that are on market are still far away from this limit.

There are some pictures of a future roadmap, where the max. wattage is bumped to 105 W.

Cheers,

Jan