Can I Y split 6-pin PCI-E for SLI

[LarryJoe]

I've posted a few times here with questions, so some of you know what I am doing. Of course I do the research after I buy the second 8800 GTX. I have one on the way, it was a Dell pull from another XPS system so it should be identical. However, I understand that each GTX requires TWO 6-pin power connections each and my Dell 750w PSU only has two. In addition, I only have two 4-pin molex connectors presently plugged into my DVD-RW drives. I am somehwat reluctant to split these several times to create four open molex connectors which I need to create two additional 6-pin connections. I really don't want to make a mess out of the case unless I have two. Both molex plugs are on the same rail, so I am not sure how this will effect power.

I bought two of these from newegg. They are Y splitters. What do you think? Will these result in underpowering the cards?

I'm second guessing this entire effort at this point and may just forgo it and sell the new card. I'm reading on SLI Zone that going SLI with the 8800 GTX will suck up my 4GB of RAM and that I should go with Vista 64bit and get new RAM. If I wanted to go > 8GB I would have to ditch at least ditch two sticks as all four slots are taken with 1GB sticks.

As much as I have the fever to upgrade, I don't want to compromise general computing performance. The machine screams right now compared to my old rig.

Thoughts?

 

[adlep]

I say, just give it a shot and see what happens.

At this point you don't have much to loose. If the 2nd card is not stable you can always sell it in a week or two and take my original recommendation in your previous post

On the other hand, the 750W PSU should be able to support the SLI setup. I know that Dell underrates power supplies in their products - so chances are that the SLI setup will work fine even when you'll use the power splitters.

I am not really sure what to think about the suggestion that the SLI sucks up the RAM....

4Gigs not enough?
Seems unlikely. Many members around here have SLI rigs and many of them run 32-bit versions of Windows without complaining.
Mare sure however that your edition of Windows is fully up to date prior installing the additional graphics card.

Again, just install it and see how it works for you, you can always sell it later on with a minimal loss...

 

[LarryJoe]

Good advice. I'll run with it. I know my PSU is powerfull enough, it's more of a question of will the PCI-E power rail have enough juice to support two cards. I am not a PSU expert by any means, but I don't see why it is OK to split a molex 4-pin rail a zillion times and not the 6-pin rail.

Also, thanks for the confirmation on the RAM and 32-bit. I may be listening too closely to some extreme gamers/hardware enthusiasts.

 

[betasub]

The "RAM issue" is that a 32bit OS can only handle 4GB-worth of memory address.

The allocation of the addresses may vary depending on your hardware, but typically your motherboard & CPU require a few MB of addresses, and then there's your video and system RAM. For a single 8800GTX 768MB, you are probably left with about 2.9-3.1GB of addresses allocatable for system RAM, but if there are two GTX then substract another 768MB from that.

 

[LarryJoe]

Thanks. So I will be left with about 2GB for Vista and Apps? Is this enough?

 

[adlep]

2.2 GB should be enough for Vista and apps.
Vista will suck up 1GB just for itself leaving you with ~ 1.5GB for games...
Should be all right.
Like betasub stated, 4GB is the max that the 32 bit OS is able to address...