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PCIe lanes switching x16 -> x8 when using sata3 SSD?

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  • Motherboards
  • SSD
  • Product
Last response: in Motherboards
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December 6, 2010 12:14:33 PM

Hi all, wasn't too sure on which subforum to use based on the relevancy of so many components. I'm looking for some knowledge and advice on the subject of PCIe lanes. So I hear with P55 type motherboards, if you're using an SSD with full sata3 enabled, it bumps the video card slot from x16 to x8 lanes. I've read a little on the subject, and I'm looking for advice in my specific situation. I was planning on getting the following parts:

mobo - ASUS P7P55D-E LX LGA 1156 SATA 6Gb/s USB 3.0 ATX
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

ssd - Crucial RealSSD C300 2.5" 128GB SATA III (SSD)
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

vidcard - MSI N460GTX CYCLONE GTX 460 1GB
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

also an i5-760 cpu that I plan on doing some OCing with, aftermarket cooler and such.

I read the article here at
http://www.tomshardware.com/reviews/pcie-geforce-gtx-48...
and it details an average 8% performance loss with a single gtx 480 when going from 16 to 8 lanes. Looks like the CPU isn't a bottleneck in a single card setup, thus the slight performance loss? What I'm wondering is, can I expect a similar performance loss with my gtx 460? Is it a significant performance loss? Are there p55 1156 socket mobos that don't have this lane switching bottleneck?

Thanks for your time.

More about : pcie lanes switching x16 sata3 ssd

a c 304 V Motherboard
December 6, 2010 2:30:22 PM

Hi treporp and welcome to Tom's fourm.

Not true, and that downgrade only happen in 1st revision of some Gigabyte mobos.
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December 6, 2010 3:30:30 PM

Hmm, it says on the asus product page:
http://www.asus.com/product.aspx?P_ID=DfyAB26HiDpiiu8f&...

Turn on IO Level Up to boost the USB 3.0 or SATA 6Gb/s data transfer rate to up to 500MB/s! Users can flexibly switch between full-speed PCIe x16 mode for their graphics cards and IO Level UP for rapid data throughput.

There are several newegg comments made fairly recently talking about this on that mobo and a few other similar asus p55's. Not sure what's going on here.
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December 6, 2010 4:45:06 PM

While this issue is still somewhat confusing to me, it looks like your mobo choice is superior. There's even a comment about how it's one of the very few mobos that offers USB3 and SATA3 without compromising PCI-e performance. Hopefully it'll deliver on that, the full potential of sata3 as well as x16 lanes simultaneously instead of one or the other, or maybe my vidcard indeed won't saturate x8 if that turns out to be the case.

Since I'm limiting myself to the 1156 socket anyways, I'll have to go with your mobo choice as my best bet, thanks for the info!
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a c 717 V Motherboard
December 6, 2010 4:59:08 PM

I often recommend the ASUS P7P55D-E PRO ; it's a clear winner. Regarding the saturation - it's not a guess - I know.

Just putting it out there -> a superior combination for +$146 {or less} is the ASUS P6X58D-E + i7 950. If you live close to a microcenter.com location then the difference is ONLY $50!!! {i7 950 = $199}. http://www.microcenter.com/single_product_results.phtml...

Yeah Buddy! :) 
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December 6, 2010 5:34:04 PM

Oh wow. Costs the same as the i5 from Newegg. I do live near a microcenter too... GAH. I initially decided to avoid 1366 due to it seeming like the main benefit was the architectural changes to allow more bandwidth for SLI setups. A high end thing beyond my care and budget. This microcenter deal takes care of the budget angle, with the cpu choice being 5 bucks less (!) and the mobo not being too much more (especially open box style from microcenter again). And yet, it seems criminal to go with a single gtx 460 in that... doesn't it?
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a c 717 V Motherboard
December 6, 2010 6:40:42 PM

Nah, the GTX 460 is fine for most games; search 'your games' against the GTX 460. Also, that MOBO will easily do 2-WAY SLI and 3-WAY SLI sooo you have room to grow! Also, the X58 is superior to the P55 chipset, and duh so is the 4-core+ 4-thread i7 950.

i7 950 QPI 4.8 GT/s - 6,328
i5-760 DMI 2.5 GT/s - 4,570

PassMark - http://www.cpubenchmark.net/high_end_cpus.html

WIN - WIN - WIN!!! ;) 
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December 6, 2010 6:51:47 PM

Man, thanks so much. I never expected I'd be changing my plans like this but you sure picked some sound deals. I'd be a fool not to get'em. So pumped! :pt1cable: 
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December 6, 2010 6:52:28 PM

Best answer selected by treporp.
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a c 717 V Motherboard
December 6, 2010 6:55:53 PM

Very Cool! Good Luck on your Build - never look back! :sol: 
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a c 304 V Motherboard
December 6, 2010 7:07:35 PM

This topic has been closed by Saint19
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