pe2900guru

OK guys I need some advice. I have a server that I'm converting to a workstation. I have a x1950pro vga card being powered off a 4-pin molex to 6-pin vga power adapter. That molex is powering two dvd burners and then my video card. I just ordered a 8800gts fatal1ty and want to power it with a different output. I'm thinking way too much power going through that one 12v wire. The main backplane board for my SAS hard drives has a 8-pin power output connector that is made for a small backup SAS backplane board. I want to convert that output to my video card. But, it has two yellow, two red, two black, and two grey 16 gauge wires on the cable. I'm thinking cool, two big yellow 12v wire and two black grounds into a 6-pin and I have it. Can I just cut the red 5v and grey power-ok wires back. Or do I need to connect the greys to power for the psu to think everything is ok? If I do? Do I connect both to a 5v or one to a 5v and one to a 12v? If so? which grey to which power? I have redundant 930watt PSU's on this thing and I don't want smoke them or my backplane. Thanks...

linderman

my friend you are "toying" with a real heart ache


while your wiring and voltage concepts are correct on how to get the power feeds you need. You totally forgot about AMPS in your plan!


if you try this adventure with your current PSU you are headed for big trouble, it doesnt have the needed horse power on seperated / isolated 12volt rails

especially to operate an 8800 GTS you need at least a high quality Antec Trio 650 watt PSU you could squeeze by with a high quality unit like the antec trio rail 550 watt, but the savings; if any, arent worth the hassle

dont shop for PSU's by price that will put you chin deep in the mud


there are other ways to skin the cat if you have a tight upgrade budget ??? expect to pay $100.00 for a worthy PSU

linderman

the 8800 is an expensive video card to risk playing with an inadaquate PSU that was not designed for that kind of isolated 12volt power

pe2900guru

I have two $400+ server PSU's in this thing. Like I said. 930 watts each. The size of these power supplies are twice as big as a normal ATX PSU and weight a ton. The connection I want to use is rated for two SAS slots at 75 watts each = 150 watts. Plus the PCI-e slot is rated at 75 watts. Total of 225 watts. NVIDIA states that the G80 core can peak at 145.5 Watts with 116.6 on average during gameplay. They recommend 450watt psu for the GTX and 400 watt psu for a GTS on a high end system. I have twice the PSU and I should have a 75+ watt buffer zone over peak draw on the connections. Max amp draw would be 12. Which gives me a 7 amp buffer on the connections. My PSU may or may not have isolated 12volt power rails. But one rail at 80amps or four at 20 amps each. It still looks safe to me. I'm just worried about overheating the wires trying to get 12 amps + through one 18 awg wire.

I just read that the grey (power OK) wires are for the low 5v and 3.3v only. Can anyone second that?

pe2900guru

POOP! After I wrote that last post my friend emailed me this link.

http://www.zipzoomfly.com/jsp/Produc...uctCode=371322

For that price it's not worth thinking about the cable convert. Hell I spent $35 on the 8-pin dell cable just to look at it. I have a extra 5.25 bay so why not. I leave a post on the VGA PSU and let everyone know if it works well or not.

linderman

Ok I must agree with you; your PSU does sound like it has the muscle to accomplish your goal

all you need is several 12volt wires and some ground wires and make the plug


dont use the grey wire for the video card


I am not as impressed with those video card. helpers! the 70% efficiency rating of them spells low quality

linderman

you are aware the 8800 GTX needs two pci connectors right ????


the 8800 GTS only needs one


I think you are headed in the right direction using the wires you were thinking of >>>>> even if you have to split of them which is what actauly happens inside the PSU anyway, as long as your solder your splices you should be fine

pe2900guru

Thanks for the fast reply Linderman, I have to use the GTS because my case almost touches the card as is. So the power plug(s) need to come out the back of the card. Not the side like the GTX. Maybe I'll try just the yellow and black wires and see if I get voltage. If not, I guess I can try a grey to red so the PSU can see the low power-ok voltage. Wish me luck. I still have a warranty so I guess I can fry one component at a time and be covered. LOL...

pe2900guru

Looks like it's working.

I just cut back and taped off the red and Grey wires. Took one of the thick yellow wires from the 8-pin and split it to two of the 6-pin. And took the second thick yellow of the 8-pin into the third of the 6-pin. Did the same with the black wires. I'm getting 12.1 VDC in all three of the 6-pin. It's running my x1950pro OK. So I hope I'm good for the 8800GTS that should be here tomorrow. I feel much better knowing I'm running the card on multiple thick 12 VDC's now.

linderman

given the backplane draws as much juice as you have stated, you will no have trouble running an 8800 gts >>>>>>>> far better than those 5.25 drive bay mini video card PSU's

phishin4dmb

So how did the video card upgrade go on your system? I just ordered my PE 2900 and looking to do the same mod! Any extra info would be great

pe2900guru

It worked out great. You must use a card like the GTS because the power connector is on the back of the card not the side. I used a x16 to x8 adapter that moves the card but you can still plug in two monitors and the s-video plug lines up with the snap bracket hole. I bought a dell backplane power cable on ebay and sliced it to the cards power cable. My PassMark score was 4430. nobody comes close.

I installed two SATA DVD-RW drives. They plug right into the MB. I used a adapter for the power.

http://www.passmark.com/baselines/topten.php

phishin4dmb

pe2900guru:

Perfect, exactly what I thought. If people only new what power they could pull on this system with this mod. Mine shows up this Friday with a 8800 GTS. Are you using buffered memory? From what I have read, you can put unbuffered/non ECC memory in. That would boost read performance, and drop write performance which would be great for a workstation which is what I am going to be using this for. Lots of video.

Thanks for the info.

Steve