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Will my PSU support Crossfire?
Hello, I apologize for the amateur question but I am new to the dual GPU scene. I currently own a Alienware Aurora R4 with an Intel(R) Core(TM) i7-3820 CPU @ 3.60GHz processor, Radeon 7950 GPU, and a DELL W299G 875W PSU. This is the generic power supply that dell sends out with most of its Alienware builds so I am sure some of you are familiar with it. I am curious if my current power supply will support two Radeon 7950's running in Crossfire. It seems my total wattage is sufficient but I am not sure if I have an extra power cable running from the PSU to connect to a second Radeon 7950. Should I purchase the second GPU or upgrade the PSU first? I appreciate any responses, I will link out the PSU and GPU exact specs below.
Dell W299G 875 PSU
Radeon 7950
speedstep
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April 24th, 2015 16:00
no it wont you need a 1000W power supply. Each 7950 uses 300W
Doctor-Spoofy
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April 24th, 2015 19:00
Thank you for the response. My current PSU claims to be 875watts, so each card using 300 watts on average would amount to 600 watts just for the graphics cards, so you are saying the remaining 275 watts would not be enough to power the rest of the hardware? I suppose 875 watts is the maximum rating, which is optimistic, so with power fluctuation it would not be enough. Would 1,000 Watts give the system enough leeway or do you think it would be just passing the minimum requirement?
kirkd
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April 24th, 2015 21:00
300 Watts is a fairly normal power supply for simple systems with low demand video. You will have only 275 watts left , which could be iffy. I would go for a bigger supply. You are correct thinking the ratings are optimistic. We had had several posters recently that could not get the expected power from their basic OEM supply.
Do a web search and see what others do with a pair of 7950s. Here's several hits:
750W (or greater) power supply with four 75W 6-pin PCI Express power connectors recommended for AMD CrossFire technology.
For a single card,the total Power Supply Wattage is NOT the crucial factor in power supply selection!!! Sufficient Total Combined Continuous Power (30 amps) available on the +12V Rail(s) rated at 45°C - 50°C ambient temperature, is the most critical factor. Therefore 60 amps for dual cards.
Doctor-Spoofy
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April 25th, 2015 12:00
Thank you for the information, I knew the power connectors were important, I just did not realize how extremely specific they were. With this knowledge in hand I will definitely be able to pick out the correct PSU.