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  #1  
Old 01-07-08, 12:28 AM
EazzyTarget EazzyTarget is offline
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GPU Pair -- Serial or Parallel

Hey guys, first post here... been reading a bit and think I've done okay so far with my parts... but wondered if the parallel path through my GPU blocks is going the wrong way.

I've designed and put together most of the following water cooling in my Cosmos 1000 case:



Resevoir

Pump

CPU

Rad 1 (Black Ice GT-XFlow 120)

T-Splitter

2x8800 Ultra GPU's in Parallel

T-Splitter

Rad 2 (Black Ice Pro 3)


My concern, from my reading, is that the Swiftec Stealth GPU blocks in parallel may have different pressures and that the water would circulate through one more than the other... creating a temerature problem in the one with less flow.

How are you guys handling 2xSLI (or more) in your cooling loops?

-EazzyTarget

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  #2  
Old 01-07-08, 03:17 PM
rrjwilson rrjwilson is offline
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I am currently running in series and i am getting serious temp issues. I have even had to knock the CPU back again from 3.7 to 3.0 because of heat created and summer being here.

Parallel splits the thermal loading and increases thermal transfer because of higher dT gradient. I believe your worries are unfounded as the pressur drop difference between identical blocks should be almost insignificant and as the rad is a partial reservoir as not all water moves through it at the same speed this will only help your situation.

May i ask what CPU you have?

I have a q6600 and 8800GTX in SLi and with one PA120.3 its toasty so if yours is quad core or even dual with slight OC I'm not sure you will get a cool running setup with those rads.
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  #3  
Old 01-07-08, 05:35 PM
EazzyTarget EazzyTarget is offline
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Quote:
May i ask what CPU you have?
Sure, I have the QX9650 -- but am not really planning to OC (famous last words).

My biggest thing was the noise from fans and the incredible heat generated by the 8800. I ran in SLI on air for a short while but the MB kept shutting down with an overtemp warning.

I will get the last of my equipment (Rad 120.1) today and can finish my loop, but I leak tested everything (else) last night for just over 2 hours and the loop idles at 103 degrees farenheit (without fans on 120.3 radiator).

So I am optimistic that *with* fans and the second smaller radiator (after the CPU) that I can get 10 degrees or so cooler at idle.

I guess only time will tell!

-EazzyTarget
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  #4  
Old 01-07-08, 05:36 PM
Toxcity Toxcity is offline
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Running without fans on your Rads?
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  #5  
Old 01-07-08, 05:44 PM
EazzyTarget EazzyTarget is offline
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Quote:
Originally Posted by name='Toxcity'
Running without fans on your Rads?
Yeah, the screws I bought were too short so I couldn't mount them last night as I had planned and the local hardware store was closed.

So, what started as a leak test / flush, turned into a "how warm will it run" test (no RAM, Hard Drives, or Audio card in the system).

-EazzyTarget

Ps. I picked up longer screws on the way into the office this morning and will mount everything tonight
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  #6  
Old 01-07-08, 05:49 PM
Toxcity Toxcity is offline
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Bet it got warm?

Good luck on the mounting. Do you think you could post some images of the finished build?
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  #7  
Old 01-07-08, 07:23 PM
EazzyTarget EazzyTarget is offline
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Quote:
Originally Posted by name='Toxcity'
Bet it got warm?

Good luck on the mounting. Do you think you could post some images of the finished build?
Well, I had the loop cycling into/out of a large pitcher so it was a lot of water to heat up which -- now that I think about it -- is probably why it only got to 103 degrees... :whack:

I will definitely post some pics when all done (later tonight or tomorrow night)!

-EazzyTarget
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  #8  
Old 03-07-08, 06:09 PM
EazzyTarget EazzyTarget is offline
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Here are a couple of pictures for you of my finished mod.





From power off to power on was just under a week of "spare time" to complete.

Which I thought was pretty good, but my my eight year old son thought was about 6 days too many since I had taken over the home theatre and he couldn't play his video games for a whole week!!!

Anyhow, everything leak tested great until I put the side panel back on... the resevoir inlet was a little loose and the side panel flexed the hose enough to create a leak...

Other than that, she seems to be working great! Pulled a 17,000+ 3DMark'06 upon power up... which I thought was GREAT.

-EazzyTarget
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  #9  
Old 24-07-08, 05:40 AM
agentx agentx is offline
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so wat kind of temps do u get now. idk if this is true but wouldnt it have been better to use dual core rads instead of single core as they dissapate more heat faster.
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  #10  
Old 24-07-08, 05:53 PM
EazzyTarget EazzyTarget is offline
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Quote:
Originally Posted by name='agentx'
so wat kind of temps do u get now. idk if this is true but wouldnt it have been better to use dual core rads instead of single core as they dissapate more heat faster.
GPU's temps are within a degree of each other at 65C when running Crysis at 1920x1200 high everything.

The CPU's cooling delta was not as good, I've seen max temps hit 54C when fully loaded -- only slightly better than what I had using air!

I don't know enough to know what the difference in the radiators would be, the HL BlackIce Pro III was described as a "2 Pass" radiator. Is that the same as dual core... I am guessing not.

Is there a radiator I could have used instead that would cool the 65C degree water coming out of the video cards better? I would love to get the CPU cooler and the NB/SB would like some water too... but I can't imagine adding them to the loop.

Thanks in advance for any feedback.

-EazzyTarget
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