My First Radeon!
- Thread starter homerdog
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Those recommendations have some built-in assumptions (read: padding) to account for the layman John-Q-Public buyer who may not understand the various power needs of a modern computer, especially if they're a novice at overclocking and don't realize what they might be doing to power consumption.
A quality 350W unit may cover it without issue, depending on the rest of your system. Example: if you're running an i5-4650 at stock speeds, a pair of "standard" memory sticks (no high-speed DDR2400 overvolted stuff), and an SSD drive along with a green 1TB or 2TB unit, then a 7950 in there shouldn't cause you any headaches at stock speeds.
If, however, you're runniing a 3930k at 5Ghz with eight sticks of ram overclocked to DDR2133 speeds along with a fat stack of drives, then a 650W power supply may not be enough to feed the beast with a single 7950, even moreso if you plan on overclocking it too.
So, the answer is "it depends"
Heh, yeah the 450W unit is a bit overkill, but there are practically no quality options in that size. Besides, I like to have a bit of headroom if I ever decide to overclock at all (just the GPU as the motherboard in that system doesn't even support overclocking the CPU).
Realistically while gaming the whole system doesn't draw over 250W, so a good 300W unit would suffice (if there were a 300W unit with enough connectors, which there is not).
BTW it is a damn fine gaming system. Runs *almost* anything you can throw at it with max settings at locked 60Hz 1080p. However since it is driving a 1440x900 monitor, it does indeed run *everything* at max settings with lots of AA
PPS it is not quite as quick as the GTX670 in my primary system, but I like the fact that it has 3GB of memory. Depending on how VRAM usage in games goes in the next year, I may swap the GTX670 for it. My bro will be fine with 2GB at 900p
PPPS my brother and his girlfriend have been playing Dead Island together, him on the new rig and her on my old one with a C2D E6750 +GTX260. I recently got an QX6700 on Ebay for $60 to put in the old rig. My first EXTREME EDITION processor LOL
Realistically while gaming the whole system doesn't draw over 250W, so a good 300W unit would suffice (if there were a 300W unit with enough connectors, which there is not).
BTW it is a damn fine gaming system. Runs *almost* anything you can throw at it with max settings at locked 60Hz 1080p. However since it is driving a 1440x900 monitor, it does indeed run *everything* at max settings with lots of AA
PPS it is not quite as quick as the GTX670 in my primary system, but I like the fact that it has 3GB of memory. Depending on how VRAM usage in games goes in the next year, I may swap the GTX670 for it. My bro will be fine with 2GB at 900p
PPPS my brother and his girlfriend have been playing Dead Island together, him on the new rig and her on my old one with a C2D E6750 +GTX260. I recently got an QX6700 on Ebay for $60 to put in the old rig. My first EXTREME EDITION processor LOL
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My "home server" has 13 hard drives in it, a PCI-E hardware-assisted raid card, a blueray reader, an i5-3570k processor at stock speeds, four sticks of 8GB / 1600mhz ram, and an AMD 7750 1GB in it. It idles at about 38W and the most I've seen it pull from the wall is about 140W under serious duress.
The smallest power supply I could buy with a quality name and modular cables was 450W from PC Power and Cooling. I didn't need that much by far, but buying an el-cheapo no-name generic unit was not in the cards for a virtual host server.
The smallest power supply I could buy with a quality name and modular cables was 450W from PC Power and Cooling. I didn't need that much by far, but buying an el-cheapo no-name generic unit was not in the cards for a virtual host server.
Uuuh, I wasn't recommending you go power a 7950 on a generic 460W PSU. Check the +12V rail on that thing. I've seen some generic "450W" PSUs that are rated for something like 220W on the +12V rail, and in reality they blow up if you try to draw even that much.
OTOH my little Silverstone 450W PSU can put out a whopping 432W on the single +12V rail, and it can go higher than that without OCP kicking in. And oh yeah, it has properly functioning OCP so it won't go pop if you do try to run all that and a hairdryer off of it
Not saying that will happen to you, but please for the love of god check the +12V rail before plugging in that 7950!
PS you should have at least 300W available on the +12V rail. They usually show how many amps it is rated for, so 300/12=15amps.
You need at least 15amps on the +12V rail to be in the "Safe Zone" IMO. If you don't have that, just order a friggin Corsair CX430 for $43.98 shipped.
OTOH my little Silverstone 450W PSU can put out a whopping 432W on the single +12V rail, and it can go higher than that without OCP kicking in. And oh yeah, it has properly functioning OCP so it won't go pop if you do try to run all that and a hairdryer off of it
Not saying that will happen to you, but please for the love of god check the +12V rail before plugging in that 7950!
PS you should have at least 300W available on the +12V rail. They usually show how many amps it is rated for, so 300/12=15amps.
You need at least 15amps on the +12V rail to be in the "Safe Zone" IMO. If you don't have that, just order a friggin Corsair CX430 for $43.98 shipped.
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Babel-17
Veteran
:waves: That's what I have, a DELL XPS with a 460 watt PSU and a HIS IceQ HD 7950. It came with an i7 2600 and 8 GB's of ram. I should mention that my HIS came with the voltage set pretty low so that maybe lets it use power more sparingly than your usual 7950. I've only overclocked it as far as 960 MHz on the core as it seems to want a lot of volts to go much higher and I'm not wild about that. I generally run it at stock (800 MHz). The memory seems to overclock higher than I need. Since I run at stock or near stock I don't bother overclocking the memory. Though HIS does allow memory voltage to be adjusted with their their tool.
http://www.newegg.com/Product/Product.aspx?Item=N82E16814161407
Edit: P.S. Reference HD 7950's, and my HIS card, use two, six pin, power connectors. Factory overclocked cards might require an eight pin connector which the Dell 460 watt PSU does not provide. So bear that in mind. Also, air flow in the XPS is decent but not designed with overclocking ones videocard in mind. That's why I went with the HIS, it exhausts the air. And finally, when overclocked, the HD 7950 starts using a lot of power and it might strain the PSU when you combine high core clocks with a high load and high voltages. So, I wouldn't count on the crazy overclocks that many get from their HD 7950's. They usually have cases with great cooling and PSU's with lots of headroom.
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There will be a large sticker on one of the sides of the PSU that lists all the different rails and how much amperage is available on each. My personal opinion is that it will probably be fine, but do check the +12V rail please. It will only take a minute
P.S. It may list multiple +12V rails. In that case, just add the two together to get the combined +12V rating and go by that. (It's actually not that simple but if it has two +12V rails it'll probly work fine).
P.S. It may list multiple +12V rails. In that case, just add the two together to get the combined +12V rating and go by that. (It's actually not that simple but if it has two +12V rails it'll probly work fine).
The sticker that Homerdog is referring to will look something like this (hope my stolen link works! )
On this sticker you will see that the +12V rail supplies up to 20A. That would be sufficient for your 7950 needs...
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On this sticker you will see that the +12V rail supplies up to 20A. That would be sufficient for your 7950 needs...
Babel-17
Veteran
http://www.stuartconnections.com/it...00-MiniTower-460-Watt-Power-Supply-7P3WV.html
Edit: Link above is for the PSU from a Dell XPS 8300. I use that for HD 7950. The picture below is of the XPS 420 PSU.
That should be it. Ironically my XPS 420 has a 425 watt PSU and what appears to be beefier spec's for watts allowed by way of 12 volt.
Edit: Link above is for the PSU from a Dell XPS 8300. I use that for HD 7950. The picture below is of the XPS 420 PSU.
That should be it. Ironically my XPS 420 has a 425 watt PSU and what appears to be beefier spec's for watts allowed by way of 12 volt.
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On the link Babel-17 provided (which is in fact my PS), the sticker lists specs for 12V A, 12V B, and 12V C. The A and B connections have sufficient capacity, but the C does not. What do these A, B, and C designations mean, and how would I know which of these I am connecting the card to?
D
Deleted member 13524
Guest
I'm thinking of getting two HD7950s crossfired with a 130W TDP Xeon E5 in a X79 board, 4 DDR3 modules, 3 SSDs and 2 HDDs.. with my very old BeQuiet 650W supply.
By my calculations, it should be perfectly fine since the supply can withstand 680W longterm at 85% efficiency, acceptable temperatures and voltage deviations under 5%... where the whole system will probably never go over 550W even when running power viruses.
So I guess it depends on the power supply. Don't go for wattage numbers as they are almost meaningless in the sub-$100 power supply market.
By my calculations, it should be perfectly fine since the supply can withstand 680W longterm at 85% efficiency, acceptable temperatures and voltage deviations under 5%... where the whole system will probably never go over 550W even when running power viruses.
So I guess it depends on the power supply. Don't go for wattage numbers as they are almost meaningless in the sub-$100 power supply market.
If you look closely you'll see that it states the combined +12V output cannot exceed 410W, and then it goes on to list the max amperage for each +12V rail.
I don't think it's possible to know which connectors run on which rails, but that PSU should be sufficient regardless. Congratulations!
BTW what you mean about the +12VC rail? It shows 18A just like the other two.
Babel-17
Veteran
I was running a HD 6870 off the 425 watt one, along with a 2.4 GHz Q6600.
I'm currently running the HD 7950 in my Dell XPS 8300 with the i7 2600.
I'm folding quite a bit with that card but at reduced clocks and voltage. At normal clocks I was logging a lot of non-stop hours playing Tomb Raider and Bioshock Infinite. Prior to that I logged a lot of non-stop hours playing Max Payne 3 with a mild overclock.
I'm not sure how the watts are distributed over the rails but if I know Dell they don't offer two, six pin, connectors unless they account for every bit of their specified power being available.
So, along with the PCIe X16 lane, that would mean 225 watts available.
I'm currently running the HD 7950 in my Dell XPS 8300 with the i7 2600.
I'm folding quite a bit with that card but at reduced clocks and voltage. At normal clocks I was logging a lot of non-stop hours playing Tomb Raider and Bioshock Infinite. Prior to that I logged a lot of non-stop hours playing Max Payne 3 with a mild overclock.
I'm not sure how the watts are distributed over the rails but if I know Dell they don't offer two, six pin, connectors unless they account for every bit of their specified power being available.
So, along with the PCIe X16 lane, that would mean 225 watts available.
D
Deleted member 13524
Guest
The HD7950 Boost has a max TDP of 225W, which is topped by any two-rail combination of those rails. You should be fine.
If you're going to use PCI-Express power adapters, just make sure you use each adapter connected to a different cable coming from the PSU.
If you're going to use PCI-Express power adapters, just make sure you use each adapter connected to a different cable coming from the PSU.
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