Information about AGP 4x slot

[knowlton]

Hello everyone -- first post on anandtech. Good to be here.

I am a total noob as far as video cards. I've been doing some research on them (trying) and I get a slightly different story from each person. I need someone to reply to this post who has a lot of practical, hands-on experience with AGP video cards.

I don't know what information is relevant, so I'll post what I can find:

I have an older system. It's about 3 or 4 years old. A Systemax "Venture" Pentium 4 at 2 GHz, with 1 Gig of SDR RAM.

Here is a link to my system specs:

http://www.supportforyourpc.co.../home.asp?sn=104922314

Here is a link to my motherboard:

http://www.biostar-usa.com/mbdetails.asp?model=U8668


The user's manual for my motherboard says I have the following AGP slot specs:

"The 66MHz AGP 2.0 compliant interface supports 1x, 2x and 4x data transfer
mode."



That is about all I know about my current system. Right now the AGP 4x slot is empty - I have never used it. I have only ever used the onboard 32 MB chip for my video.



So, what I am wanting to know is, given the age and limitations of my system, and the fact that this may be the one and only time I upgrade to a new video card -- what should I put in the AGP slot?


I have been getting a lot of conflicting information. Each person I talk to says something different.

I have heard that you can buy 8x cards and they will work in the 4x slots just fine -- they just "clock down" to the 4x speed.

Other people tell me, that's not true. That you have to be careful. Not all 8x cards will work right in a 4x slot.

It can't be both ways. Do 8x cards work?


Also -- as far as putting an 8x card in the slot -- assuming I can find one that does work right. Can I take advantage of 512 MB of RAM (given my system limitations above) or would that be a total waste of money because my system would not be able to make use of it? Or would I be smarter to go with 256 MB of video RAM.


What about 64-bit vs 128-bit cards and my motherboard.


I've heard that the motherboard cares very little what is on the CARD itself, as long as it is the right card for the slot and the card stays cool.


I hope all of this helps you help ME make an informed decision.

 

[Cutthroat]

Welcome to AT forums

What catches me in your post is you don't mention why you want to upgrade to an AGP card if an onboard GPU was doing sufficiently so far. What made you decide that you need an AGP card?

AFAIK 8x AGP cards will work in a 4x AGP slot, ther may be some cases where I'm wrong, it's been a while.

AGP cards are more expensive than thier PCIe counterparts, they are produced in small batches because there is little demand for them anymore. This makes me think you need a good reason to be getting an AGP card.

IF you were to buy an AGP card I would suggest something like EVGA E-GEFORCE 7600GS AGP 400MHZ 256MB 700MHZ DDR2 DVI-I VGA HDTV Out Video Card

 

[knowlton]

cutthroat:

LOL. I guess I didn't think that "why" I wanted to upgrade was relevant to the discussion. It is really just a matter of wanting to "because I can". Also, I want to experiment with C# / XNA game development and to do so, I need a Shader Model better than 1.0. Plus, it might be nice to play some higher end games that require more than 32 MB of RAM.

If I could afford to, I would just get a newer computer, but I can't do that right now.

So that is that.

I noticed the card you recommended is only 256 MB.

Won't a 512 MB card work? They have those for around $65.

 

[Cutthroat]

I picked that one because it's a top seller, it's a mid-range DX9 card that should support enough features to do what I'm expecting you would do. 256MB or 512MB video RAM probably won't matter much, but the more the better.

 

[knowlton]

Originally posted by: Cutthroat
I picked that one because it's a top seller, it's a mid-range DX9 card that should support enough features to do what I'm expecting you would do. 256MB or 512MB video RAM probably won't matter much, but the more the better.

Thank you.

Tom

 

[darckhart]

what matters is if the 8x agp card you plan to buy is agp 2.0 voltage compliant, which in most cases for newer cards they are not. speedwise 8x agp cards are backward compatible, physical slot keying is compatible, but voltage signaling may not be, since agp 2.0 is 1.5V and agp 3.0 is 0.8V. so basically, check to make sure the 8x agp card you buy can work at 1.5V.

 

[knowlton]

Originally posted by: darckhart
what matters is if the 8x agp card you plan to buy is agp 2.0 voltage compliant, which in most cases for newer cards they are not. speedwise 8x agp cards are backward compatible, physical slot is compatible, but voltage signaling may not be, since agp 2.0 is 1.5V and agp 3.0 is 0.8V.

THAT is the kind of information I needed to know!!!!

My slot is 2.0 for sure.


So what cards will work? Does anyone know of any that will be 1.5V ?

 

[Peter]

The above isn't really accurate.

Short of design fsckups on either end, plugging 8x cards in 4x slots, and 4x cards in 8x slots ALWAYS works since the signalling uses the same voltages. 8x mode just uses less "voltage swing", which is popularly mistaken for an actually lower signalling voltage - which it is not.

Supply voltage on AGP has always been the same anyway, so just go ahead and use any card you please. The one thing to mind is card power consumption - an AGP 4x slot does have to provide the maximum allowed power for any AGP card ... but your system's power supply unit may not be adequate.

 

[knowlton]

Originally posted by: Peter
The above isn't really accurate.

Short of design fsckups on either end, plugging 8x cards in 4x slots, and 4x cards in 8x slots ALWAYS works since the signalling uses the same voltages. 8x mode just uses less "voltage swing", which is popularly mistaken for an actually lower signalling voltage - which it is not.

Supply voltage on AGP has always been the same anyway, so just go ahead and use any card you please. The one thing to mind is card power consumption - an AGP 4x slot does have to provide the maximum allowed power for any AGP card ... but your system's power supply unit may not be adequate.

How can I tell if my power supply is up to the challenge?

What will I be looking for when I crack my case open?

 

[Peter]

Look at how much current (in Ampère) it can source on the 3.3V rail. This rail is (almost) exclusively used by the AGP card.

 

[knowlton]

Originally posted by: Peter
Look at how much current (in Ampère) it can source on the 3.3V rail. This rail is (almost) exclusively used by the AGP card.

The "rail" ?

What is a rail?

Dumb it even further down for me, please.

 

[Peter]

PC power supplies have several output circuits, e.g. 3.3V, 5V, 12V. These are called "rails", and their individual load limits are usually listed on a sticker on the PSU.

 

[knowlton]

Originally posted by: Peter
PC power supplies have several output circuits, e.g. 3.3V, 5V, 12V. These are called "rails", and their individual load limits are usually listed on a sticker on the PSU.

Peter:

I appreciate the replies I've gotten so far - from everyone.

I get the feeling you know what you are talking about.

Okay, so, you've seen my motherboard and specs. You know my PC is 3 to 4 years old. You know it is a P4 2.0 GHz.

Assuming my power supply is up to snuff, and I wanted to play the best "graphics intensive" game possible...what card would I want to get?

Where is that line drawn as far as what my antiquated system can handle vs the best possible card I could put in the 4x slot, for under $80?

Tom

 

[Peter]

Well ... it should be a DirectX9 card at least, but overdoing it won't help much because a really fast card would mostly sit there twiddling thumbs, waiting for more input from the slow processor.

I don't really know what's currently on offer in AGP form, but as a rule of thumb I'd say going beyond $120 would be a waste.

As for power consumption, the size of the fan/heatsink is a good indication.

http://www.newegg.com/Product/...x?Item=N82E16814102711
http://www.newegg.com/Product/...x?Item=N82E16814161210

 

[hooflung]

An ATI(AMD) X1650 or Nvidia 7600GS will do you good. Just make sure they have 128 bit memory interfaces. No 64bit crap. You should be able to find exactly what you need on newegg. PS... stay away from World of Warcraft now that you have a PC that will run it decently..

 

[Crassus]

Hooflung, you wouldn't happen to have any personal knowledge of that, would you?

Anyway, comparing what I remember the performance numbers to be, you may actually gain more by checking ebay for some older generation top of the line cards, like a decent 6800 GT. It's a wee bit dated, but I think it will run faster than a 7600. And you should be able to get it used for a lot less.
It's also able to use the DX9 codepath in games - I'm not sure it is really lacking anything in terms of features. In terms of onboard RAM and with of the path to the RAM go with the highest you can find for a reasonable price. It's not so much a question of whether it will work in your system, it's more a question of whether the rest of your system can keep up

But something else I want to point out from personal experience: it might be worthwhile to get a really really cheap basic AGP card first to test if the slot is actually functional. A friend of mine had a computer from (I think it was Dell or the like, back in the i440BX days), that had a non-functional agp slot on it.

 

[knowlton]

Originally posted by: Peter
PC power supplies have several output circuits, e.g. 3.3V, 5V, 12V. These are called "rails", and their individual load limits are usually listed on a sticker on the PSU.

I cracked-open the case and the sticker inside which lists my system details says I have a 250 Watt Power Supply.

On the Power Supply itself, I could only make-out the following information:

(reading across from left to right

450W

then in the next column it said:

Current
Max Combined
Wattage

then in the next column it said:

213 W | 240 W
430 W

then in the next column it said:

9.6 W | 2.5 W | 10 W
22 W


I'm not sure how all that info equals "250 W"


Does this answer the "rail" question? That's the best I can do short of removing the power supply.


Tom

 

[knowlton]

Here is some more (hopefully helpful) information:

When I go to Display Properties / Settings and look at the Screen Resolution in the lower left -- the maz resolution I can set it to is 1600 x 1200. Is that a restriction of my integrated 32 MB video card -- or is that a limitation of my current monitor?

Just thought I would throw that out there, see if it mattered.


I am still trying to figure-out if I should go 256 MB or 512 MB


I notice the cards have different clock speeds? For my system -- which clock speed would be TOO FAST for my system? No sense in getting a 800 MHz card if I can't even make use of 400 MHz, right?