How many 1U servers can I run with 20 amps?

[mockingbird]

I'm thinking of setting up an older 1U server in someone's rack, but he pays for a maximum of 20 amps and I am concerned that it will overloaded.

OTOH, with two 1U servers already running, the meter is only showing 2A.

Let's assume there will be five servers with 4 harddrives on each, let's say each server is drawing no more than 300W. All the information I've read so far leads me to believe it should not be a problem, but what concerns me is that with video cards, people suggest there should be two rails that supply at least 15A each. If one high end video card can draw 30 amps, how can these servers be drawing such a minute amount?

[Th3_uN1Qu3]

Re: How many 1U servers can I run with 20 amps?

If one high end video card can draw 30 amps, how can these servers be drawing such a minute amount?

A server does not have a high-end video card. Actually, some have no video card at all. Also there isn't a whole lot of dissipation capability in a 1U case, so if it's 1U you can bet it's power efficient. Or has some darn noisy fans.

[mockingbird]

Re: How many 1U servers can I run with 20 amps?

So you're telling me that these videocards really draw 30 amps when I'm playing Movie Battles II maxxed out at 1280x1024 and chugging away at 30fps? I have a Radeon 2900XT, the thing is a power hog I hear, though I do have a 750W PSU in that PC.

[Th3_uN1Qu3]

Re: How many 1U servers can I run with 20 amps?

12x30=480w. Not too hard to believe. Tho i believe it applies to today's high end, the 2900 is quite old.

A quick google reveals a consumption of about 350w for the 2900.

[severach]

Re: How many 1U servers can I run with 20 amps?

A Kill A Watt is a cheap way to get an instant answer.

[smason]

Re: How many 1U servers can I run with 20 amps?

WTF? A video card drawing 30A? Holy excrement!
I'm not a gamer so I normally ignore high end video cards, but 30A?
A 100W 20 metre HF transmitter barely gets to 20A.

[Krankshaft]

Re: How many 1U servers can I run with 20 amps?

A thing to mention the Kilawatt meters aren't true RMS.

They claim to be on the package but when I hooked one up to my modified sine wave (square wave) UPS inverter and pulled the plug it registered 0 volts. I commend it for giving up and not registering some fictional voltage that is too low but I wish they wouldn't have lied on the package.

Back on topic I believe you're referring to video card current draw from the PSU?

Yes at full load they can draw up to their max current it depends on how graphics intensive the game is. A graphics card is just a GPU like a CPU the more it's loaded the more current it will draw.

But servers don't have high end graphics cards they're not designed for that.

[santel]

Re: How many 1U servers can I run with 20 amps?

So you're telling me that these videocards really draw 30 amps when I'm playing Movie Battles II maxxed out at 1280x1024 and chugging away at 30fps? I have a Radeon 2900XT, the thing is a power hog I hear, though I do have a 750W PSU in that PC.

No possible way a video card draw 30 Amps, that would be like 500Watts + cpu etc etc = 800Watts. will require a 1000Watts supply or more.

[PlainBill]

Re: How many 1U servers can I run with 20 amps?

I'm thinking of setting up an older 1U server in someone's rack, but he pays for a maximum of 20 amps and I am concerned that it will overloaded.

OTOH, with two 1U servers already running, the meter is only showing 2A.

Let's assume there will be five servers with 4 harddrives on each, let's say each server is drawing no more than 300W. All the information I've read so far leads me to believe it should not be a problem, but what concerns me is that with video cards, people suggest there should be two rails that supply at least 15A each. If one high end video card can draw 30 amps, how can these servers be drawing such a minute amount?

You're getting confused between current drawn from the AC line (at 120 VAC) and current drawn by a video card (at 12VDC). If your video card is drawing 30 Amps, that's 360 Watts. Assuming the power supply is 80% efficient, that's less than 4 Amp from the AC line.

PlainBill

[PCBONEZ]

Re: How many 1U servers can I run with 20 amps?

TDP of CPU(s) [in watts] x 1.25 [The 1.25 is for VRM efficiency/losses]
+plus+
5 to 15 watts/stick of RAM depending on what kind it is. [Google it]
+plus+
20 watts/HDD [typical watts on spin-up from dead stop]
+plus+
35 watts for basic mobo power [approximation used in most PSU calculators]
+plus+
10 watts/add-in card [general slot power is +5v, slots limited to 2 amp on +5v]
+plus+
5 watts/LAN chip [wild guess]
-divided by-
PSU effieciency
=Equals=
Pretty Darned Close [in watts]

Skipped Opticals because when in use the HDDs are already spun-up from a dead stop and using much less than the 20 watts.

.

[PCBONEZ]

Re: How many 1U servers can I run with 20 amps?

The steady state condition is not what you should look at.
Look at what they pull when starting up.....
.