Rocketfish Power Supply

[Homey D. Clown]

Is anyone here using or has used or know anything about rocketfish power supplies?
I work for bestbuy and we just got some 700w ones in. They retail for 169.99 but with my employee discount I cant get one for a lot less then that. I didn't really have much time to totally check out the specs on it but the one thing I did notice was that it says it has 4 12v. rails? When I looked it up in our system supplier comes up as Huntkey Hong Kong?

 

[silent-circuit]

Err.... don't know about them, but I wouldn't, personally.

First up: multiple rails are not really a positive, though they're marketed as such. Here's the deal...

Multiple rails can cripple your PSU, especially in the case of low-wattage CPUs and high-wattage videocards, which is a pretty typical configuration in gaming PCs today. An Intel Core2Duo can draw as few as 65 watts at full load, clocked at spec speeds (not overclocked). A Geforce 8800GTX or Radeon 2900HD can pull as much as 200+ watts, but 180 watts can be typical under full load, especially depending on the temperature of the surroundings.

Rails are rated in amps, which are measures of true electrical power. Amps = Watts / Volts, so A=W/V. Talking about 12 volt rails, you get A=W/12. 20 amps on a 12 volt rail (which is the minimum suggested by Nvidia to run an 8800GTX) then equals 240 watts. It only pulls about 16 amps under load at worst with stock clocks, or ~190, but that's still a ton of juice. With 4 12v rails, that power gets split 4 ways.

So, assuming you get 70% of the rated capacity on the 12v rails, which would be descent. 700 watts, you get 490 watts across 4 rails or a little less than 41 amps. They may not be evenly distributed, with 1 or 2 lower than the other two, but in the interest of keeping things comparatively simple we'll assume they are, with 2 to PCI-E connectors, 1 to motherboard/ACC, and 1 to the CPU itself via the 8 pin plug (assuming you're working with a newer Intel).

A 700 watt PSU probably has 4 PCI-E connectors, and probably has a rail feeding each pair of 2. Assuming you get 50% of the 490 watts or 41 amps on all the 12v rails to those 2 rails feeding the PCI-E connectors for video cards you get 244 watts total, 122 watts for 2 PCI-E connectors, 122 watts per 8800GTX, or about 10 amps each. As all PCI-E cards draw from the PCI-E slots as well as the connectors, that should be sufficient (though pushing it a little), but the issue is that with ~4-5 amps draw from each card for a combined 8-10 amp draw on the motherboard rail in an SLI system. Assuming 25% of 490 watts for the motherboard's 12v rail, or another 10 amps.... where's the motherboard or other accessories (whatever is connected to the rail which ends up being pulled from in addition to the PCI-E connectors) going to get power? It isn't, more than likely. The PSU, if well-built, will shift draw to the PCI-E connectors to compensate, but this will only work to a certain degree. Massive system instability may ensue, and cash goes down the drain.

Now this is obviously a worst case scenario, meant to show exactly why you don't want a bunch of 12v rails, things tend to work out better, but that doesn't mean they're a good idea. If a supply needs to split up rails in order to maintain stable power (which is normally a big selling point with this sort of thing -- claiming less DC ripple due to multiple rails) chances are you shouldn't trust it with your hardware anyway. There are obvious exceptions -- the Enermax Galaxy series, for example -- but they tend to be more about flash than getting things done.

With a single 12v rail, every 12 volt device in the system draws from the same main "source". So if 70% of the total wattage is available on the 12v rail, those watts/amps can all go where they're needed, none are "lost" or wasted, and one rail can't be overdrawn due to absence of power on another. I am (obviously, as I bought one) partial to PC Power and Cooling, partly because all their supplies are single-rail designs. My 750 watt continuous supply has 60 amps or 720 watts available on the 12v rail. Given almost everything in a PC is 12v, having that much of the total capacity on the 12v rail makes a lot of sense.

Hope this didn't seem too pedantic or rambling... and I guess in the end it didn't really answer your question.

Short version:
Never heard of them, wouldn't trust them, get a single rail if you're running high-end stuff, something from Seasonic, PC Power and Cooling, Enermax, or similar. Paying more is worth it when it means you avoid fragging all your stuff.

 

[Homey D. Clown]

ok, i've never been able to find anywhere where it was explained in a way I could understand, now I get it, thanks.One of the other reasons I asked was like I said I work at bestbuy and most of the guys who work in the computer dept. dont know crap! I'll admit i'm no expert but even I have had to correct some of the misinformation they've given customers. Maybe the next time I work i'll get more info on the specs of this power supply.

 

[jonnyGURU]

RocketFish IS Best Buy. It's an in house brand like Dynex.

 

[DeFex]

Avoid at all costs! Go to a real computer store and buy the best one you could get with the same money you would have spent.

 

[bustaplz]

ok, i've never been able to find anywhere where it was explained in a way I could understand, now I get it, thanks.One of the other reasons I asked was like I said I work at bestbuy and most of the guys who work in the computer dept. dont know crap! I'll admit i'm no expert but even I have had to correct some of the misinformation they've given customers. Maybe the next time I work i'll get more info on the specs of this power supply.

Don't ask the PCHO guys, ask an agent.

EDIT - Woah, I just bumped a thread from the graveyard. My bad, I got linked to it and didn't check dates. Ignore me!

 

[NickS]

Anyone got a pic of the label so I can see who the OEM is.

 

[jonnyGURU]

Oh joy... how did I miss this first time around?

Multiple rails can cripple your PSU, especially in the case of low-wattage CPUs and high-wattage videocards, which is a pretty typical configuration in gaming PCs today. An Intel Core2Duo can draw as few as 65 watts at full load, clocked at spec speeds (not overclocked). A Geforce 8800GTX or Radeon 2900HD can pull as much as 200+ watts, but 180 watts can be typical under full load, especially depending on the temperature of the surroundings.

Wrong. Those graphics cards don't pull that much power.

Rails are rated in amps, which are measures of true electrical power. Amps = Watts / Volts, so A=W/V. Talking about 12 volt rails, you get A=W/12. 20 amps on a 12 volt rail (which is the minimum suggested by Nvidia to run an 8800GTX) then equals 240 watts. It only pulls about 16 amps under load at worst with stock clocks, or ~190, but that's still a ton of juice. With 4 12v rails, that power gets split 4 ways.

20A is what Nvidia suggests for the ENTIRE PC. It's not what the card alone pulls. They're suggesting that your PSU have at least 20A for the ENTIRE PC.

So, assuming you get 70% of the rated capacity on the 12v rails, which would be descent. 700 watts, you get 490 watts across 4 rails or a little less than 41 amps. They may not be evenly distributed, with 1 or 2 lower than the other two, but in the interest of keeping things comparatively simple we'll assume they are, with 2 to PCI-E connectors, 1 to motherboard/ACC, and 1 to the CPU itself via the 8 pin plug (assuming you're working with a newer Intel).

A 700 watt PSU probably has 4 PCI-E connectors, and probably has a rail feeding each pair of 2. Assuming you get 50% of the 490 watts or 41 amps on all the 12v rails to those 2 rails feeding the PCI-E connectors for video cards you get 244 watts total, 122 watts for 2 PCI-E connectors, 122 watts per 8800GTX, or about 10 amps each. As all PCI-E cards draw from the PCI-E slots as well as the connectors, that should be sufficient (though pushing it a little), but the issue is that with ~4-5 amps draw from each card for a combined 8-10 amp draw on the motherboard rail in an SLI system. Assuming 25% of 490 watts for the motherboard's 12v rail, or another 10 amps.... where's the motherboard or other accessories (whatever is connected to the rail which ends up being pulled from in addition to the PCI-E connectors) going to get power? It isn't, more than likely. The PSU, if well-built, will shift draw to the PCI-E connectors to compensate, but this will only work to a certain degree. Massive system instability may ensue, and cash goes down the drain.

That's not how it works. You have a single +12V source that's split into four and then each of those four have a limit on them. If the limit is exceeded, power isn't shifted, systems don't become unstable... the PC just shuts down. But since 20A is more than enough power for a pair of 6-pin PCIe connectors, it's a non-issue.

Now this is obviously a worst case scenario, meant to show exactly why you don't want a bunch of 12v rails, things tend to work out better, but that doesn't mean they're a good idea. If a supply needs to split up rails in order to maintain stable power (which is normally a big selling point with this sort of thing -- claiming less DC ripple due to multiple rails) chances are you shouldn't trust it with your hardware anyway. There are obvious exceptions -- the Enermax Galaxy series, for example -- but they tend to be more about flash than getting things done.

But splitting up the +12V doesn't improve stability. It's a safety measure. It's done as a backup to short circuit protection when a short has too much resistance for the protection to see.

With a single 12v rail, every 12 volt device in the system draws from the same main "source". So if 70% of the total wattage is available on the 12v rail, those watts/amps can all go where they're needed, none are "lost" or wasted, and one rail can't be overdrawn due to absence of power on another. I am (obviously, as I bought one) partial to PC Power and Cooling, partly because all their supplies are single-rail designs. My 750 watt continuous supply has 60 amps or 720 watts available on the 12v rail. Given almost everything in a PC is 12v, having that much of the total capacity on the 12v rail makes a lot of sense.

Ah.... PCP&C user. Got it.

Doug's "myth" on this is easily debunked FUD whenever you're discussing a PSU with four or more +12V rails.

Here's factual information: http://forums.anandtech.com/messageview.aspx?catid=84&threadid=2167846&enterthread=y

Don't ask the PCHO guys, ask an agent.

EDIT - Woah, I just bumped a thread from the graveyard. My bad, I got linked to it and didn't check dates. Ignore me!

Yeah. What were you thinking?????

Anyone got a pic of the label so I can see who the OEM is.

It's Huntkey. In fact, it's a Huntkey Titan 650W. 700W? No. And to add insult to injury, when Huntkey says "650W" they mean "650W peak." It's really 550W continuous. So how Best Buy came to the conclusion that this PSU can do 700W is beyond me.