- Dec 10, 2013
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R9 290x crossfire
- Thread starter Classrobbie
- Start date
Solution
vmem
Splendid
- Feb 17, 2012
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I wouldn't do it
each of your GPUs is 250W, which is 500W right there. your CPU is designed to pull 125W at stock, totally 625W.
that would only leave 75W left over for the rest of your system, including mobo, ram, all harddrives, mouse, keyboard, external accesories, etc etc.
even if you can do it, maxing out your PSU's capacity is never a good idea. you'd want a 1000W PSU for 290X crossfire
each of your GPUs is 250W, which is 500W right there. your CPU is designed to pull 125W at stock, totally 625W.
that would only leave 75W left over for the rest of your system, including mobo, ram, all harddrives, mouse, keyboard, external accesories, etc etc.
even if you can do it, maxing out your PSU's capacity is never a good idea. you'd want a 1000W PSU for 290X crossfire
RedJaron
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- Sep 20, 2011
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TDP is NOT how much power it actually draws. The 8120's power consumption really depends on how you overclock it. Tom's did a test on overclocking an 8150 and found the system total ( including drives and an idle Radeon 6850 ) ranged from 200W to 360W ( however, I don't know if that's draw from the wall or from the PSU, but I think it's from the wall. ) Estimating 90% efficiency from the PSU, that's 180W - 270W for the system. Estimating 30W idle draw of the 6850 leaves 150W - 240W, depending on overclock.
Yes, the 290X will peak around 250W, so that's 500W peak GPU load. Technically, a real good 650W could juuuust run the system at stock clocks, but I too think a little headroom is in order. A good 750W like this SeaSonic would do quite nicely. I wouldn't go below 700W on the 12V rail though.
If you want even more peace of mind, step up to the 800W range. However, you don't need a 1000W PSU.
vmem
Splendid
- Feb 17, 2012
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I understand TDP is not how much power a CPU actually draws, but it is typically sufficient to get the CPU to run stably. with 125W to 130W available, he can TURN ON his machine and it can run. as for OC that is out of the question.
the reason I would recommend a 1000W or near there is for efficiency's sake and peace of mind. a PSU does slowly degrade overtime, and this is accelerated by increased heat and running it at 100% or near 100% capacity. if he does need to purchase a new PSU, a 900W+ would be prefered IMO. but yes, I do agree that a 750W high quality PSU would cut it.
also, don't forget to take HDDs etc into account. an average HDD can draw something like 10-13W on load, which isn't insignificant in this scenario. to make matters worse, things like a backlit keyboard etc can all draw significant amounts of power. personally, I like to keep things under 80% load of the PSU max capacity if possible... just my two cents
the reason I would recommend a 1000W or near there is for efficiency's sake and peace of mind. a PSU does slowly degrade overtime, and this is accelerated by increased heat and running it at 100% or near 100% capacity. if he does need to purchase a new PSU, a 900W+ would be prefered IMO. but yes, I do agree that a 750W high quality PSU would cut it.
also, don't forget to take HDDs etc into account. an average HDD can draw something like 10-13W on load, which isn't insignificant in this scenario. to make matters worse, things like a backlit keyboard etc can all draw significant amounts of power. personally, I like to keep things under 80% load of the PSU max capacity if possible... just my two cents
RedJaron
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Modern PSUs are designed to have maximum efficiency between 50% and 85% load ( and the 80 Gold rating mean they stay 90% efficcient above 80% load. ) Below that threshold they're very inefficient. And yes, they do wear down from heat and use, and that goes for every other part in a system, so I don't see your point. So long as you're not running a PSU at 95% load with no ventilation, you're not going to kill it prematurely.
Let's go over the math again. Two 290X at peak power draw 250W a piece. However, at normal gaming levels they rarely go over 200W. And once again, I said the total system draw in that benchmark was around 150W. That includes drives. But no, the average drive today does not draw 10W - 13W on load. That's actually the very high end. Average load is closer to 7W-8W for a 7200rpm, though the Caviar Black does push 9W on heavy writing. So, adding that all up, at stock clocks and peak load, the system as a whole will draw ~650W. However when you're enjoying games and not running Prime95 torture tests, system load will drop down around 525W. That's a 70% load on an 750W PSU and only 62% on an 850W. Neither one will be run into the ground. on the contrary, that's right around the 50% load on a 1000W unit, which is not where you usually want to be.
If you are planning on running the 8120 as high as it can go and the base system will be drawing 200W or more, than you might want to look into the 900W range. But still no need for the 1000W range.
Let's go over the math again. Two 290X at peak power draw 250W a piece. However, at normal gaming levels they rarely go over 200W. And once again, I said the total system draw in that benchmark was around 150W. That includes drives. But no, the average drive today does not draw 10W - 13W on load. That's actually the very high end. Average load is closer to 7W-8W for a 7200rpm, though the Caviar Black does push 9W on heavy writing. So, adding that all up, at stock clocks and peak load, the system as a whole will draw ~650W. However when you're enjoying games and not running Prime95 torture tests, system load will drop down around 525W. That's a 70% load on an 750W PSU and only 62% on an 850W. Neither one will be run into the ground. on the contrary, that's right around the 50% load on a 1000W unit, which is not where you usually want to be.
If you are planning on running the 8120 as high as it can go and the base system will be drawing 200W or more, than you might want to look into the 900W range. But still no need for the 1000W range.
vmem
Splendid
- Feb 17, 2012
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modern PSUs only lose efficiency below 20% load. especially with 80+ Gold, they're generally 90% efficient or at least 88% even at 20% load. it is when you go below that that you really lose efficiency.
at the end of the day, I think I just prefer to have more headroom on a PSU than you. and I agree that neither would run the system to the ground. I see your logic and it's fine. in the end we can agree to disagree. I believe the OP has more information than he needs anyway
at the end of the day, I think I just prefer to have more headroom on a PSU than you. and I agree that neither would run the system to the ground. I see your logic and it's fine. in the end we can agree to disagree. I believe the OP has more information than he needs anyway
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