Amperage Info directly from ATI

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Jiggaman2576

Limp Gawd
Joined
Oct 27, 2004
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I just picked up the X1900XT and flashed it to the XTX, then I overclocked it. Then I had system problems, not from overclocking, but from power. I bought me a 700 watt OCZ gameXstream PSU to help alleviate the power demands but it has only 1 18A 12V rail for use with accessories such as hard drives/cd roms and such. The 2 video card connectors each have 18A of power on the 12V line, and the ATX connector gets 18A on the 12V line. Where am I going with this?

I called ATI to find out just how much power is drawn from the 12V line so that I could pick between my 600 watt OCZ that is 36A on the 12V line, or the 700 which has 18A dedicated to the GPU. This is when I got a big shock. The guy from ATI told me that the X1900XT requires by itself, not the whole PSU, but just the card itself, 24A on the 12V line. OK, that is rediculous! So the 700 watt OCZ is not recommended for ATI cards because its 6 amps lower then what the card requires at STOCK SETTINGS. I am overclocking mine to the 9's and wasn't sure what the deal was, well now I know.

In short, if you get the X1900XT be sure as hell to get a friggen awesome PSU that has rediculous amperage on your 12V line because that is the only line that feeds these cards through the video connector. I now have to figure out how to get 2 PSU's to feed my hungry system. 12 hard drives, a DVD-R, 20 Cold cathodes, a water pump and 9 120mm fans turns out draws more then 18 amps :(

Time to custom make some cables for this beast just to keep it on.
 
that really depends on the quality of the power supply ,

i have a enermax noisemaker 600w , two 12v rails 18a each ,

i had the x1900xt flashed to xtx and overclocked to the max ~749/846 ,

havent had any problems with power ,

there arent many people that run 12 harddrives, 9x120mm fans , water pump and the rest of the stuff off of one power supply and expect the overclocked x1900xtx to get enough juice,

you need a 1000W power supply for a system like that
 
Theres is no psu that i know of that has more then 20amps per rail, im running an xtx on a enermax 485w psu.
 
The new PCP&C Silencer 750 has 60 amps on the 12v line. And only cost $199.00...
 
plywood99 said:
The new PCP&C Silencer 750 has 60 amps on the 12v line. And only cost $199.00...
Click to expand...

Thats rediculous.

I guess it must have a No.2 gauge wire size on the connector as well?

I call BS
 
The XTX wouldnt need 24 amps on teh 12v rail. That would be 288 watts alone, plus the other its uses pushing it over 300w. An X1900 anything doesnt need 300w of power (and thats triple the 7900 GTX uses).
 
BBA said:
Thats rediculous.

I guess it must have a No.2 gauge wire size on the connector as well?

I call BS
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Nope, totally legit. Remember with wire gauges and amps, length plays a very important role. Now in a car audio system using 15 feet of wire, 10 gauge or less would be Highly reccommended, but for the short run in a computer case, it would not be needed.

And this is PCP&C were are talking about, they don't put out crap claims like other psu vendors...
 
DarkBahamut said:
The XTX wouldnt need 24 amps on teh 12v rail. That would be 288 watts alone, plus the other its uses pushing it over 300w. An X1900 anything doesnt need 300w of power (and thats triple the 7900 GTX uses).
Click to expand...

QFT. Maybe ATI is using FUD to make sure a powerful enough supply is being used...
 
plywood99 said:
The new PCP&C Silencer 750 has 60 amps on the 12v line. And only cost $199.00...
Click to expand...
Well, I'll be damned - that's a pretty good price for such a powerful unit from PCP&C. What's the catch?

I imagine this ATi tech just gave out a bum answer. Make another call, to another tech, and see how vastly different his number is.
 
BBA said:
Thats rediculous.

I guess it must have a No.2 gauge wire size on the connector as well?

I call BS
Click to expand...
For someone with a wicked screen name like BBA, you should know how amazing PC P&C are.
 
Actually, the ATI tech mentioned PC&C right off when I told him I was having a power issue. I did tell him that 24A on 1 rail is just crazy. As I have it now, my OCZ 600 watt is running my board/cpu/gpu and thats it. The 700 watt OCZ now has a connector with some standard molex connectors on it for some of my other devices. I made one lastnight from an old mobo that I had laying around. I put 6 sata drives on the atx connector and the other 6 on the regular device lines. They are also running the lights/fans/pump. It all works fine, I checked my voltages lastnight and they are all in alignement so I shouldn't have any problems. Running stable after I removed my Auzentech Xplosion 7.1. I was getting bsod's and hard freezes with it in there. I have to get a new sound card to replace my new sound card now :(
 
I call BS from the ATI guy. If that were true, they would not be able to certify any power supplies for crossfire 1900's; 24a * 2 = 48, which is greater than the max output for the 12v rails on any of the PSUs they have listed---not even counting any necessary system components (ie, 2.5a for an HD, etc..).
 
I'm willing to bet that number is the recommended power for a crossfire setup. Cut it in half and 12A per card wouldn't be entirely unreasonable and is within specs of the 12V rails on most cards.

PC P&C 1KW
------------------------------
+5V @ 30A
+12V1 @ 16A (CPU)
+12V2 @ 16A (Drives)
+12V3 @ 36A (Graphics)
+12V1,V2,V3 = 66A (70A peak)
-12V @ 0.8A
+3.3V @ 30A
+5VSB @ 3.5A
continuous power = 1000W
peak power = 1100W
 
Anarchist4000 said:
Cut it in half and 12A per card wouldn't be entirely unreasonable and is within specs of the 12V rails on most cards.
Click to expand...
Actually what the people in this thread are saying is 24A per card....but I think you might be on to something. I wonder if the tech told the OP the wrong number accidentally. When he said each card needs 24A, he may have been quoting the total draw of a 2x Crossfire setup. I'm betting this is what happened.
 
Would someone here call ATI and post what you find? Its only about a 20 minute wait. I called bull to, and the guy refused to budge. I asked specifically if 24A was required between the different rails, like 5V and 3.3V and he said no, it only uses the 12V line and it requires 24A to be certified. So yes, that would be 48A for a crossfire setup. That is insane, and that is what the guy told me. If you call BS, great, call ATI and see what they say! Believe me it wasn't the number I wanted to hear. According to ATI tool when I overclock my card to 720/820 it draws around 32A of power. At stock it draws around 24A. If that is all 12V then he isn't full of it, but I can't believe that it is and he must have said it wrong or been misinformed.
 
Jiggaman2576 said:
Would someone here call ATI and post what you find? Its only about a 20 minute wait. I called bull to, and the guy refused to budge. I asked specifically if 24A was required between the different rails, like 5V and 3.3V and he said no, it only uses the 12V line and it requires 24A to be certified. So yes, that would be 48A for a crossfire setup. That is insane, and that is what the guy told me. If you call BS, great, call ATI and see what they say! Believe me it wasn't the number I wanted to hear. According to ATI tool when I overclock my card to 720/820 it draws around 32A of power. At stock it draws around 24A. If that is all 12V then he isn't full of it, but I can't believe that it is and he must have said it wrong or been misinformed.
Click to expand...


He is full of it. A Radeon 1900XTX draws 120 watts in gaming. OC'ed will use more yes, but even 2 stock would barely be touching 24A from the 12v, lets alone one. They do use alot more than the 7900GTX does, but if someone at ATI is telling you it uses 24A per card then they deserve to be fired, right now.

http://www.xbitlabs.com/articles/video/display/geforce7900gtx_6.html
 
Digital Viper-X- said:
I remember ATI tool reporting that my XTX was drawing 38A of power o.0
Click to expand...

it might have been drawing 38A at the core voltage (1.4V for these cards?). That would mean ~55 watts of power. Sounds about right.

Anyway, no way in hell does it need 24 amps. They probably mean that the ENTIRE SYSTEM pulls 24 amps, which is more reasonable.
 
Also keep in mind it could be pulling some power through the PCI-E slot and not all through the extra connector. That could inflate the numbers a bit from what the rails are listed at. I guess you could pull 10-12A through the connector for each card so that figure could be right but that's a ton of power.
 
krameriffic said:
I'm running my X1900XT just fine on a 500W Allied with 20A on the +12V rail.
Click to expand...

and I'm running a 512mb X1800XT (nearly identical power draw) on a neopower 480 with 15A on the second +12V.
 
plywood99 said:
Nope, totally legit. Remember with wire gauges and amps, length plays a very important role. Now in a car audio system using 15 feet of wire, 10 gauge or less would be Highly reccommended, but for the short run in a computer case, it would not be needed.

And this is PCP&C were are talking about, they don't put out crap claims like other psu vendors...
Click to expand...


Your confused.

It is cross sectional area that matters. (Well Cross sectional area, resistance and maximum temperature the given conductor can operate at is the complete answer)

-The only effect a longer wire has is more resistance, which can be seen as a voltage drop due to high current.

Dont believe me? Simple, go look at some automotive amplifier design fuse assemblies and compare a 30 amp to a 60 amp.

I have not seen any single wire in a PC or it's power supply that is capable of handling 60 Amps of current. The 60 Amps they are talking about may be a number play on instataneous peak to peak voltages or some other marketing crap. It is definitely NOT a measurable single current value.
 
Eva_Unit_0 said:
it might have been drawing 38A at the core voltage (1.4V for these cards?). That would mean ~55 watts of power. Sounds about right.
Click to expand...


That is exactly right, that is the core current at core voltage, and can be supplied by less than 5 Amps on the 12 V line.
 
Doesnt the XTX use slower ram timings? you better to flash the bios with your current bios and just modify the core and ram speeds.
 
BBA said:
Your confused.

It is cross sectional area that matters. (Well Cross sectional area, resistance and maximum temperature the given conductor can operate at is the complete answer)

-The only effect a longer wire has is more resistance, which can be seen as a voltage drop due to high current.

Dont believe me? Simple, go look at some automotive amplifier design fuse assemblies and compare a 30 amp to a 60 amp.

I have not seen any single wire in a PC or it's power supply that is capable of handling 60 Amps of current. The 60 Amps they are talking about may be a number play on instataneous peak to peak voltages or some other marketing crap. It is definitely NOT a measurable single current value.
Click to expand...

I don't think you followed me. When I said 10 gauge or less, I'm refering to the gauge number, aka 10gauge, 9 gauge, 8gauge, etc. The number is less but the wire diameter is larger.

I have plenty of real world experience working with wire and electricity. The wire run in a psu may be 24" or so. That being the case a smaller diameter wire can be used. Your fuse example is perfect. The very short distance in the fuse allows a small diameter conductor to be used.

And why are you talking about a single wire? This is a psu, you know, with multiple 12volt connectors. 24pin atx, 8pin cpu, multiple drive connectors, blah blah blah. The currunt will not be flowing through a single wire...
 
Could my problem just be that ATI's drivers are not very stable? I still am getting random hard freezes. Sometimes during games, sometimes just browsing the web. So much for a sweet QuakeCON machine. I'll have to turn my monitors off at night so people don't see my embarresing BSOD. Anyone here going to quakecon want to help me diagnose and fix this problem?
 
Jiggaman2576 said:
Could my problem just be that ATI's drivers are not very stable? I still am getting random hard freezes. Sometimes during games, sometimes just browsing the web. So much for a sweet QuakeCON machine. I'll have to turn my monitors off at night so people don't see my embarresing BSOD. Anyone here going to quakecon want to help me diagnose and fix this problem?
Click to expand...


Your sig states you are overclocking your 3800 to 2.65ghz. Try running at stock and see what happens...
 
The reason I haven't lower my CPU to stock is that it was running fine with a 7900GT that I had overclocked the piss out of with volt mods. The system ran stable and has always run stable up until now. I am reinstalling windows as I type this, but I have the old friggen service pack 1a CD so I'm going to be updaing windows forever. So far though no lockups and no bsods. I haven't installed any of the video/audio drivers yet, waiting for windows to be updated fully first.
 
Jiggaman2576 said:
The reason I haven't lower my CPU to stock is that it was running fine with a 7900GT that I had overclocked the piss out of with volt mods. The system ran stable and has always run stable up until now. I am reinstalling windows as I type this, but I have the old friggen service pack 1a CD so I'm going to be updaing windows forever. So far though no lockups and no bsods. I haven't installed any of the video/audio drivers yet, waiting for windows to be updated fully first.
Click to expand...

Maybe the reinstal will help, but still you can't blame the card/drivers untill it fails at stock. What may be stable for one card may not be for another. I'm talking from experience here, having used sli'd 7800gt's before my 1800xt and now 1900xt.

You can also use Sysprep instead of a reinstal to rid yourself of old hardware drivers, much simpler and less time consuming...
 
overclocks degrade hardware - meaning your CPU may work great for X time, the suddenly become unstable afetr X time doing certain X things.
 
Load of crap... My oc'ed X1800XT runs just fine on my Xclio 450W and I'm running 3 hard drives, 2 Sunon 38MM thick 120mm fans, 2 Aspire 120MM fans, a dvd burner and an oc'ed 3400+. My roommate's running my old XTX on an Antec TrueBlue 480W and is running 2 hard drives. But 12 hard drives, water pump, and all those fans... 700 isn't enough, probably.
 
I found the problem. For some reason with the ATI hardware I had to adjust my ram timings. FYI the 700 watt OCZ gameXstream will power the ati card just fine however it cannot power up 10 sata drives and 2 IDE drives. It will power up 10 hard drives however. I have all my mobo/cpu/gpu/hard drives on the 700 watt, except 2 sata drives wich are on the 600 watt and it appears to run with no problems. I may still have a CPU stability problem, prime95 ran all night on 1 core but only 37 minutes on the other. I did lower my Vcore a tad so I can try putting it back where it was. I am still confused why ram timings would change due to a video card, but I've proven that it was infact that. BF2 would fail to load at 62% loading any level, just drop back to the desktop. Tweaked the timings using someone else's timings on DFI-Street.com for the ram I have and sure enough, loaded right up, running smooth as silk at 1920X1440 with 4X AA and 16X AF set in the ati control panel. I am a happy f'ing camper now, I can goto quakecon with some confidence in my rig. Thanks for all the help guys!
 
I was about to chime in that my x1900xt runs fine on an overclocked amd64 with an antec 500 watt modular. It comes with the 1050 case.
 
Jiggaman2576 said:
I found the problem. For some reason with the ATI hardware I had to adjust my ram timings...I am still confused why ram timings would change due to a video card, but I've proven that it was infact that. I am a happy f'ing camper now, I can goto quakecon with some confidence in my rig. Thanks for all the help guys!
Click to expand...


Glad your system is stable. This is what I was alluding to about different hardware. It's the way drivers are programmed that will make the difference. The NV drivers were fine with your old settings, which were not 100% stable.

Always run a system at stock first to rule out hardware issues. Then up the clock...
 
I'm glad the problem was figured out. I still can't agree with the power/current thing ATi said.


plywood99 said:
I don't think you followed me. When I said 10 gauge or less, I'm refering to the gauge number, aka 10gauge, 9 gauge, 8gauge, etc. The number is less but the wire diameter is larger.

I have plenty of real world experience working with wire and electricity. The wire run in a psu may be 24" or so. That being the case a smaller diameter wire can be used. Your fuse example is perfect. The very short distance in the fuse allows a small diameter conductor to be used.

And why are you talking about a single wire? This is a psu, you know, with multiple 12volt connectors. 24pin atx, 8pin cpu, multiple drive connectors, blah blah blah. The currunt will not be flowing through a single wire...
Click to expand...

Ok

True the current flows through 3 parallel 12v wires on the PCI-e power connector. I would still bet you can not load the power supply to full current on all it's 12V circuits without damaging the PSU or melting the wiring. It takes a lot to make a 720 Watt power supply. Just look at any high current amplifier's power supply, the transformers alone won't even fit in a PC's PSU housing.

My fuse analogy was not interpreted correctly by you, a larger fuse link is needed for higher current, even though it is so short. The reason fuses are much smaller than the wire gauge they protect is because they are designed to melt before the wiring does, same theory on fusible links, it is too small to carry the current so it melts when too much current is drawn. This is solely due to resistance in the wiring, and even pure copper has resistance. The only way to push high amounts of current through small diameter wire is to control the temperature the wire will operate at (or use a superconductor).

I'd say a minimum of 10 GA single wire is needed for 30 Amps at 12v, so would three parallel 18 to 24 GA wires work? Probably not for long.
 
You bring an interesting point BBA... perhaps you should email PCP&C and see what they say about it then post it in this thread and on the other correct forums. I would do it but evidently I dont know enough about wire gauges to ask informed questions.

~Adam
 
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