Putting GTX 680 in PCI-E 2.0 x8 slot for better CPU cooling worth it?

[hans030390]

I'm not entirely sure which section of the forums is most appropriate for this question, but it does involve GPU performance and is most relevant to that in my mind. Either way, I have a single GTX 680, 2500k (4.5GHz at 1.35v) with a True Spirit 140 cooler, and Biostart TZ77XE3 motherboard.

The motherboard was designed a bit poorly in that I can't put a GPU in the top PCI-E slot if I have my TS140 turned so the fan blows air towards the rear of the cage. The cooler is too wide and conflicts with the GPU. Instead, I have to turn the CPU cooler so that the fan blows towards the top of the cage. There isn't much room between the fan and the back of the GPU that way.

My CPU temps aren't great like this. At full load, my CPU temp tops out around 68-69C, though it averages in the mid, mid-high 60s. This should be technically safe for most usage, but it's still higher than I'd like and not as cool as the TS140 should be capable of.

I can only assume that turning the cooler so it blows towards the rear of the cage will provide better performance. I've already tried remounting and reapplying paste in its current orientation.

I do, however, have a PCI-E slot below that, but it only operates in x8 mode. It's a PCI-E 3.0 board, so I'm not sure if this would mean x8 for just 3.0 or x8 for both 2.0 and 3.0. Having the CPU that I do, I can't take advantage of 3.0.

Assuming the second slot will run the GTX 680 in 2.0 x8 mode, would moving the GPU to this slot and the slight performance decrease be worth a cooler CPU? I believe TPU did a test with a single GTX 680 and found it only dropped performance by about 3-4% compared to 3.0 x16. Thoughts?

 

[lopri]

I would say so. It depends on boards so test it out yourself. Its a fairly simple procedure so you should be able to find it out rather quickly. Chances are you will not see much, if at all, performance difference. How far away is the 2nd PEG (x8 electrical) from the top PEG?

 

[hans030390]

I suppose I could test...I just don't always have the spare time necessary to test it out with multiple benchmarks and games. There are two x1 slots between the top slot and this other one I could potentially use. See picture below:

http://media.bestofmicro.com/Z77-Express-Ivy-Bridge-Value,J-Q-345446-13.jpg

 

[Termie]

http://www.anandtech.com/show/5458/the-radeon-hd-7970-reprise-pcie-bandwidth-overclocking-and-msaa

Take a look at the PCIe 3.0 x4 numbers above. That's what you'll be experiencing, approximately. There will be some bottlenecking. But you need to check the specs on your board. It should list whether that slot is 2.0 or 3.0.

By the way, I've been interested in the True Spirit 140. Is the fit issue specific to your motherboard or is it too wide to use with any motherboard's first slot?

 

[Ampersand38]

By the way, I've been interested in the True Spirit 140. Is the fit issue specific to your motherboard or is it too wide to use with any motherboard's first slot?

This Biostar board has the top slot as an x16. Most other designs I've seen has the top slot as x1, and the second as x16 to avoid this exact issue, as well as the gpu blocking the ram levers.

 

[NTMBK]

I'd say try it out and benchmark it, honestly. It's hard to guess how these things will turn out. If it bottlenecks it too badly, you always have another options- sell your 2500k and buy a 3570k/3770k. You should get a decent price for a "known good" overclocker, so the upgrade cost shouldn't be too high.

 

[lavaheadache]

Those load temps are perfectly fine for the cpu esp. if those are temps while running prime or the likes. The cpu will typically never get that hot on day to day usage. I would rather settle with those temps than run that card in a lesser slot.

 

[njdevilsfan87]

I ran 2.0 8x for a little while with a GTX 680 due a dedicated PhsyX GPU. The performance loss was almost nothing, even with it heavily overclocked.

 

[hans030390]

It looks like Dirt 3 is the only game that really sees a noticeable drop in performance. I don't even own Dirt 3. I think I'll give it a shot and see if it helps with CPU cooling and do some benchmarks with the GPU! The key is finding extra time to do it, haha.

Termie, as answered already by someone else, this is just an issue specific to my motherboard...and probably other motherboards with the top PCI-E slot being the x16 one.

Am I correct in thinking that even if the second slot is 3.0 x8, this does not mean it will do 2.0 at x16? I know the performance is the same between the two, but I'm not sure about other limitations...

 

[tweakboy]

Don't do that my friend instead just downclock the card. gl