NVIDIA 7800 not booting

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ph1re

Junior Member
Nov 28, 2006
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I just recently bought a 7800 GS OC AGP and now my system won't boot.

For my motherboard I have a MachSpeed (Same as Jetway it seems?) S755MAX

http://www.motherboard.cz/mb/jetway/S755MAX.htm
http://www0.shopping.com/xPF-M...hlon-64Bit-Motherboard

For my PSU I have a POWMAX 400w Max LP-8800D

http://www.powmax.com/8800D.htm

Now, for my motherboard I set the AGP volts to 1.8v which is what I read somewhere that the videocard I bought needed. Now I can't even boot with that videocard.

My bios for the S775 are A03 07-01-2004


I'm really bumming right now because I don't know if I bought a broken card on ebay (which I doubt I did because the guy seemed trustworthy. Or if my SiS chipset is not compatible, or if I just need to buy a new PSU. Please help. :)
 
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ph1re

Junior Member
Nov 28, 2006
15
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Alright, I contacted the seller and he said that supposedly the video card I bought (EVGA GeForce 7800 GS OC 256mb AGP) requires 0.8v and I found out that my motherboard only has 1.5 to 1.8.

Would this be the reason my videocard refuses to boot?

I don't want to buy a new motherboard (very low budget) if it's not going to fix the problem.
 
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ph1re

Junior Member
Nov 28, 2006
15
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It seems the motherboard needs to have 0.8? And mine doesn't? Any suggestions guys...
 
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cprince

Senior member
May 8, 2007
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I think that your power supply is cannot handle this card. The graphic card gets its power directly from the power supply anyway, so the voltages on the AGP slot don't matter. The 0.8V they are talking about is the voltage for the graphic core, which is derived from the 1.5V of the AGP 4x/8x slot http://en.wikipedia.org/wiki/Accelerated_Graphics_Port
I would drop the AGP voltage back to 1.5V since this is the AGP standard.
 
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cprince

Senior member
May 8, 2007
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Originally posted by: ph1re
My PSU has 25A on the 12v rail though.
Click to expand...

I don't think that you should trust what it said. According to powmax's website, your power supply delivers: +3.3@28A, +5@30A, +12@25A. I have an Ultra 500W power supply that delivers: +3.3@20A, +5@32A, +12@28A. So I think that powmax is lying about the spec of your power supply. By the way, I used to have a powmax 450W that could not run my ATI Radeon X1300 AGP; that's why I got the Ultra.
 
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ph1re

Junior Member
Nov 28, 2006
15
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Alright, but it should at least have enough power to boot into POST? I was reading an EVGA manual and came across pictures of different AGP slots, 1.0/2.0/and 3.0 Well, my slot does not have the 3.0 notch in it, it has none. So I'm guessing I do indeed have a 2.0 Universal and not a 3.0. I mean I'm all up for getting a new PSU, but that won't fix the problem
I have. As I have no money to buy both the motherboard and the PSU. That motherboard I'm getting is only 30$ so it won't put me too far back.
 
esquared

esquared

Forum Director & Omnipotent Overlord
Forum Director
Oct 8, 2000
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I am 99% certain that it's your motherboard. I had the same problem with a board at work that needed the AGP 3.0 compliance for the card to work. If your board doesn't support 8X AGP, the card won't work.

AGP on wiki

scroll near the bottom.

This will help to see the differences on what will run and their backward compatibilities. *X card in a 4X slot?

Another link here

Isn't AGP backwards compatible?

Yes, and No. Older 2X AGP cards do not use the right voltage to function properly in the newer 1.5V AGP slots. If forced into a 1.5V AGP slot, a non-1.5V compliant video card will damage the motherboard. On the other hand a 1.5V AGP card is usually backwards compatible with older 2X AGP slots.

What is .8V AGP?

.8V is the voltage requirement of new 8x AGP cards utilizing AGP specification 3.0. Motherboards supporting 8x AGP support both 1.5V AGP 2.0 compliant cards (AGP 4x) and newer .8V AGP 3.0 compliant cards (AGP 8x). The keying for AGP 3.0 cards is identical to that of AGP 2.0 cards to retain backward compatibility. A motherboard that supports 8x AGP should work fine with a 1.5V (AGP 4x video card), and a motherboard that supports 1.5V (AGP 4x) video cards should work ok with a .8V video card (AGP 8x), however in the later example the video card would only work at the fastest speed the motherboard supports (AGP 4x).
 
rise

rise

Diamond Member
Dec 13, 2004
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as much as i'd distrust a powmax psu, i dunno why you'd be messing with voltages in your bios for your agp slot unless your oc'ing. what was the "auto" setting or whatever you changed?
 
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ph1re

Junior Member
Nov 28, 2006
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The auto was 1.5, but that was before I learnt that the voltage had to be 0.8 not 1.8. And it seems I have AGP 2.0 anyways so once I get that motherboard all should be fine I hope?
 
rise

rise

Diamond Member
Dec 13, 2004
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read what esquared linked-

Motherboards supporting 8x AGP support both 1.5V AGP 2.0 compliant cards (AGP 4x) and newer .8V AGP 3.0 compliant cards (AGP 8x).
Click to expand...
your mobo linked supports 8x agp.

i'd put the bios to "auto" (personally, i'd clear cmos like wiht any hardware change) and see what happens. if it still borks, then remove any unnecessary components. if you can get a psu to swap out, good but just start at defaults first, makes things alot easier.
 
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ph1re

Junior Member
Nov 28, 2006
15
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Yeah, I had started with defaults. The motherboard I linked also is not the same exact one I have, the one I have I can't find anywhere. It's a Machspeed S755MAX Rev. 1
 
rise

rise

Diamond Member
Dec 13, 2004
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It's a Machspeed S755MAX Rev. 1
Click to expand...
where are you getting that from? look on the board itself for something, usually a sticker, with something, anything. how can you not be able to link your mobo? oh ebay, lol. i'm only kidding....
 
esquared

esquared

Forum Director & Omnipotent Overlord
Forum Director
Oct 8, 2000
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Originally posted by: rise
read what esquared linked-

Motherboards supporting 8x AGP support both 1.5V AGP 2.0 compliant cards (AGP 4x) and newer .8V AGP 3.0 compliant cards (AGP 8x).
Click to expand...
your mobo linked supports 8x agp.
Click to expand...

That board might say it supports 8X but OP said that board isn't exactly his either. OP also said himself that he has the Universal AGP 2.0 slot, Picture here which is a 1.5V slot. It's not keyed and does not support 0.8 Volts. He said that his EVGA card is 0.8 volts. that will never run on a 1.5 V slot.



Signaling Voltage incompatibility
Because speeds must be backwards compatible, Signaling Voltage is where incompatibilities arise. Basically:

* All 8x cards are 0.8v AGP 3.0 spec
* 8x cards will fit in 1.5V slots, and can tolerate the voltage, but will NOT run properly
* 4x cards can be either 1.5V or 0.8V
* 2x and 1x cards are either 3.3V or 1.5V
* Except in the case of the 8X cards, using the wrong voltage card with the wrong motherboard can result in damage in card and board
* If you install a card of incompatible voltages with the motherboard's specs, the card will NOT run

edit:
If the AGP slot isn't keyed to be even AGP 2.0 compliant it won't work for AGP 3.0 either. AGP 2.0 and 3.0 are keyed in the same spot on the AGP slot. If he really has the AGP 2.0 Universal slot (not keyed), it will never work. At worst, he could damage the video card.
 
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ph1re

Junior Member
Nov 28, 2006
15
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Oh, and when I bought the motherboard who knows how many years ago, the box said Machspeed, ect. ect., and on the motherboard itself it's labeled Rev 1.0.
 
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