X58 SSF with Crossfire - Heat

[Skulltrail]

Hello,

I have just placed an order for the following:

Case: Lian Li PC-V351B
Motherboard: Asus Rampage II GENE uATX
CPU: Intel Core i7 920 D0
Cooler: Noctua NH-U9B SE2 Duel-Fan
RAM: 3x 2GB Corsair Dominator DDR3-1600MHz CAS7
GPU: 2x 1GB Asus Radeon 5770
Boot SSD: 60GB OCZ Vertex 2E (R: 285MB/s, W: 275MB/s)
Storage HDD: 2TB Hitachi Saturn 7200RPM
PSU: 750w Corsair HX750
Optical Drive: Sony dual-layer DVD-RW with Lightscribe
Card Reader: Lian Li CR-36B
Fans: 2x 120mm Akasa Apache Black

While it definitely all fits, I am concerned about the heat, especially of the 5770s. I considered the Vapor-X models, but I really need a rear-exhausting card, which the Vapor-Xs don't, so I though that would negate any temperature differences.

I have seen others who have put two GeForce 280s in SLI in the same case with with a 1366 i7, so presumably they will run hotter than the 5770s?

Anyway, my questions are:

Will the heat be prohibitive, to the point of affecting stability? The 5770s will be at stock, and I am hoping to get the 920 to 3.3 to 3.5GHz or so.

Will a single 5870 be substantially cooler than the Crossfire 5770s? I would prefer to avoid this due to the expense.

Thanks in advance!

EDIT: Just realized the title should read SFF not SSF - typo

[alsenior]

in my mini p180 2 4890 vapour x card were constantly over heating. i would save your sanity and go for 1 5870 rather than have one card crash suddenly see you frame rate drop by half until the card cools down.

[jim]

Agree with Alsenior.

You might save a bit of cash, but it's really not worth the hassle.

[Hawker1986]

+1 on both the prev posts, in a SFF heat is a significant consideration, and reducing the number of heat producing items is only ever a good thing, even if cost goes up slightly, in the long run youll be glad you did it, Also you could happily then run back to a 550-650W PSU which will save a few bob in turn.

Hawker

[Skulltrail]

Thanks guys - looks like I may well be doing that. Regarding the PSU I went for the 750 over the 650 due to its extra quietness - I figured fans will be running pretty high so I didn't need to add to the din via the PSU. Also, I thought that if it was running with a lighter load it would itself be cooler. Not sure if that was correct though?

[jim]

Not really, electricity = heat. Whether the PSU has a higher capacity or not can never change that.

You don't need anything like 650 watts, let alone 750. 500 would be ample.

[Skulltrail]

I specced it up here and it came to 602W with the CPU @ 3.55GHz with 1.25v and 20% capacitor aging: http://www.antec.outervision.com/PSUEngine

Admittedly its unlikely that everything will be at 100%, but at 525W, that's right in the quiet zone of the HX750, here: http://www.corsair.com/products/hx75...oise-chart.gif

Also, I noticed that when two 5770s are in Crossfire it required 569W (single 490W) rather than the 602W with a 5870. Struck me as strange.

[jim]

Hexus build pulled 465W at full load - i7 @ 4GHz, with two 5870s in Crossfire.